Curtis’s Speed GED » Graphs

GED Math: Taking a Closer Look

Curtis — Tue, 10 Nov 2009 02:14:43 +0000

S’up y’all. Ready for some more GED Math?

I been thinkin’ about how sometimes we think we know the answer without looking at the whole problem, you know? Check this out.

Super Subs Inc. is planning on hiring new employees for the summer. They want to make sure their new employees are available to work on the busiest day of the week. Below is a chart of their four different stores, and how many sub sandwiches they sold at each store the previous week. According to this chart, which day will the new hires most likely need to work?

1. Wednesday

2. Thursday

3. Friday

4. Saturday

5. Sunday

I usually like takin’ short cuts, right? But you can’t depend on short cuts. You gotta make sure you’re right, or you’ll get taken for a ride.

First, we gotta make sure we know what we’re lookin’ for. The question’s askin’ what day is most important for new employees to work. The most important day is when they’re sellin’ the most, right? So, next thing is to check out is on which day they’re sellin’ the most subs. When I first look at this chart, I just scan through and see that in the first row, for store “A,” they’re sellin’ the most on Friday. Bam, that’s the answer, right? Wrong. Scannin’ a chart real quick is a good strategy to get information, but you always gotta double check. Check out stores B-D. They’re sellin’ more subs on Saturday. Since there’s three stores that sell more on Saturday, and only one that sells more on Friday, now we can make a better guess that Saturday’s the answer we’re lookin’ for. But let’s double check again to make sure.

Add up all the subs sold on Friday at all the stores. It’s 489. And Saturday is 560. In fact, you don’t even need to really add all those up straight up, you can just estimate and get 490 for Friday and 570 for Saturday. See, we were right, even with simple estimation, we can see they sell way more subs on Saturday. Since we scanned first, then double checked, we can be sure we got the right answer now. It’s 4. Saturday.

So check out this next question.

Super Subs Inc. may need to shut down a store due to the bad economy. According to the chart, which store would they most likely shut down?

1. Store A

2. Store B

3. Store C

4. Store D

5. None of the Stores

Remember, we can’t just take a guess lookin’ at the first column of numbers. What y’all think the answer is?

For more information about the GED test and GED test preparation, visit the GED Academy at http://www.passGED.com

GED Math: Graphing Points and the Coordinate Plane Grid

Curtis — Mon, 17 Nov 2008 23:30:03 +0000

Hey guys! I got something about the GED math test that you gotta know. The test’s got mostly multiple choice questions, about 80%. But there’s 20% of the questions that ain’t multiple choice, in those questions, you got two different types. I’m gonna give you the low-down on one of em, the “coordinate plane grid.” You prolly got no idea what dat is. Well, here’s the 411.

Here’s what the coordinate plane answer grid’ll look like on your GED answer sheet:

So, what’s it for? The questions that use this grid ask you to graph a point. Just a dot. That’s all. The point is, where is it? That’s all they want to know. One of these 49 dots is the answer. Well, that’s a big margin for guessin’, jus’ 2% chance to get it right. (How’d I figure the percent chance? If you mark one bubble outta 49 bubbles, that’s a 1 in 49 chance of getting the right bubble… and 49 rounds to 50, multiply both sides by 2 and you got a 2 in 100 chance. That’s 2%. Okay, that’s a sidetrack.)

A “coordinate plane” is jus’ a graph of where something is in comparison to two lines, an x-axis (a line going right and left), and a y-axis (a line going up and down). The two axes are marked “x” and “y” on your graph.

A point you’d want to graph on here would be written like this: (3, -2). The first number is the x, and the second number is the y. To find the point, go to +3 on the x axis:

And then go DOWN 2 (so you’re across from -2 on the y axis):

The point you’re at is (3, -2).

Pretty easy. On the test, the values of x or y can only be 6, 5, 4, 3, 2, 1, 0, -1, -2, -3, -4, -5, or -6. There won’t be any fractions, decimals, or other numbers. So, if you think you know the answer, but it doesn’t fit on the grid, try again!

Another thing, you’ll only fill in only one circle on the grid. The answer to the question will be one single point. Okay, try this GED practice question, using the coordinate plane grid:

In the equation y = 2x + 3, show the location of a point where x = -2.

How’d you do on this? Did you figure it out? They give you one part of the point, -2, but they don’t give you the whole thing. You’ve got to put -2 into the equation for x to find out what y is:

y = 2(-2) + 3

y = -4 + 3 (Hint: A negative number times a positive number gives you a negative number)

y = -1 (Hint: To add a negative and a positive number, subtract the numbers and then give it the sign of the BIGGER number, so -4 + 3 = -1, but 4 + -3 = 1. Don’t let negative numbers throw you on the test!)

So, the point you want to graph is (-2, -1), like this:

Go learn that GED math!

For more information about the GED test and GED test preparation, visit The GED Academy at http://www.passGED.com.

GED Question from Austin: Quadratic Equations and Graphs

Curtis — Mon, 10 Mar 2008 19:00:37 +0000

Whoa. Austin’s really into the hard stuff. Here’s his question:

hi im austin.
i have a question on some things. im having trouble with the quadratic equations and graphs. the quadratic equation i just cant seem to understand quite that well. The graphs…well i just cant figure out how to solve the slop of a line and everything else. You think you could maybe give me some good advice on an easy way to understand everything about quadratic equations and x and y axis graphs.

Part 1: Quadratic Equations for the GED

Yeah, this is the hard stuff. Quadratic equations… the good news is, you won’t have a lot of them on the GED test. The first thing is, what is a quadratic equation, anyway? It’s an equation with x squared in it, basically. Usually, it has something x squared, plus or minus something x, plus or minus a number, equals something. Like: x² + 3x – 4 = 0

Quadratic equations are hard to solve. I’m just gonna deal with the easier ones, those’ll be the kind on the GED. That means, there’s no number before the x squared. When you get an answer, there’s gonna be two possible numbers for x, because of the square. That’s because a square root can be negative or positive. So -1 squared is 1, and 1 squared is also 1.

There’s a big, confusing formula for finding x in a quadratic equation like this one. But there’s also a shortcut. The best way to solve these (the simple ones, that is, which are the ones on the GED), is to factor. That just means, find two things that multiply together to equal the equation. To do this, you’ve kind of got to work backwards. Your factors are going to look like this: (x + ?) (x + !) = 0. Remember, the question mark and exclamation mark can be negative or positive numbers.

If you multiply out (x + ?) and (x + !) you get x² + (! + ?)x + (! times ?).

It don’t matter what the numbers are… the number by the x is going to be your two numbers added together, and the number without the x is going to be the two numbers multiplied together. So, if the example is this: x² + 3x – 4 = 0, what two numbers can multiply together to get -4? (You take the minus sign and put it with the 4. That’s the big stumbling block…) You can multiply 4 times -1, or -4 times 1, or 2 times -2.

So, which of those, added together equals the middle number, +3? It’s 4 and -1. So, x² + 3x – 4 = (x + 4) (x + -1)

So, (x + 4) (x + -1) = 0. That means, either x + 4 or x + -1 will equal 0. The possible answers for x are -4 and 1, the opposite signs of your numbers. Did you follow all that?

On the GED, it can be easier to try the answer choices in the equation, to see which ones are right. For more about quadratic equations, check out:

http://www.themathpage.com/alg/quadratic-equations.htm

http://www.purplemath.com/modules/quadform.htm

http://plus.maths.org/issue29/features/quadratic/index-gifd.html

Part 2: Graphs for the GED

x and y axis graphs… well, here’s the deal. Any kind of equation with two variables (an x and a y) can be graphed as a line. Lines’ll have different shapes, depending on the equation. You’re really askin’ about graphs of lines. That means, there’s no squares or anything funny in the equation. There’s an x and a y, and the line is made up of all the possible numbers for x and y that can make the equation true.

For x = y, the numbers for x and y will always be the same. So, if x =1, then y = 1. If x = 2, y = 2. The line will be a straight line on a graph where all the x’s equal all the y’s. Okay, it’s easier to look at it. Go here to get a great intro to graphing lines:

http://library.thinkquest.org/20991/prealg/graph.html

So, you asked about slopes. That means, how steep is the line on the graph, and what direction does it go? So, the slope’s got two parts, and the answer to those questions is put into a number.

First, how steep is the line? You can figure it out by picking two points on the line, and seeing how far UP and then how far OVER you’ve gotta go to get from the first point to the second. Divide how far you went UP by how far you went OVER. That gives you a number.

Then, which direction is it going? Going from bottom to top, does it lean to the right? Then the slope’s a positive number. Does it lean to the left? Then the slope’s a negative number. Here’s a link you can go to to practice finding the slopes of some lines.

Slope Practice Worksheet: http://www.algebrahelp.com/worksheets/view/graphing/slope.quiz

Also, check out more about graphing here: http://library.thinkquest.org/20991/alg2/graphs.html

You can also figure out the slope just from an equation, if it’s said in a particular way, called Slope Intercept form. Slope Intercept form has the number for the slope in it, and the number for the y-intercept (where the line passes through the y axis, or where x=0). It goes like this: y = mx + b

m = slope, and b = y-intercept

So, if your equation is y = 2x + 3, then the slope is 2. Makes it easy to find, huh?

Here’s a cool page lettin’ you see how the Slope Intercept form looks like as a line:

http://id.mind.net/~zona/mmts/functionInstitute/linearFunctions/lsif.html

Here’s some practice making lines using Slope Intercept form:

http://www.algebrahelp.com/worksheets/view/graphing/slopeintercept.quiz

For more information about the GED test and GED test preparation, visit The GED Academy at http://www.passged.com.