So I’m wanting to go back to school in the spring but I need to take a placement test first and well I can hardly remember anything with the math section! I’m trying the practice questions and I just can’t remember how to do this stuff. This is the website to the practice questions. http://www.act.org/compass/sample/pdf/numerical.pdfI’m having trouble figuring out questions 7,8,12,13, and 14 under the algebra section.Then here’s the website for more sample math questions.http://www.act.org/compass/sample/pdf/geometry.pdfFor this one I need lotsss of help. Questions 3,4,6,7,9 and then 5,6,8,9,10,11 and then all of the trig section.If you can only help me on even just one question I would appreciate that very much, I definately need it.
Aw I am so sorry for you to have wasted your time but I already knew those. I need help with those questions under the algebra section towards the bottom. I really appreciate your help though!
Bri wrote:Aw I am so sorry for you to have wasted your time but I already knew those. I need help with those questions under the algebra section towards the bottom. I really appreciate your help though!Whoops! I didn’t see that there were two sections. Let me take a look at those.
- Find the factors of x^2 - x - 20.I had a college professor once teach me a great trick for figuring these out. Unfortunately, I’ve forgotten it. Think of the original polynomial as being made up of three variables, R, S, and T. The polynomial can be expressed as R + S + T. (In this case, S and T will both be negative, which will change the addition to subtraction.) There will be two factors in the solution to this: (A + B) x (C + D). R will equal A times C. R = X^2. Since the only thing that is going to make R = x^2 is two Xs, but A and C must equal X. That’s the easy part.T will equal B times D. Since T equals negative 20, your options are -1 and 20, 1 and -20, -2 and 10, 2 and -10, -4 and 5, or 4 and -5.S is a little more complicated. It will equal B x C plus A x D. Since you already know A and C must both be X, you only have to worry about B and D. You know from the polynomial that B+D must equal negative 1. Of all the candidate numbers for B and D, only 4 and -5 sum to -1.This gives you your two factors: (X + 4) (X - 5). Answer A.
- Find the factors of X^2 - 5X - 6.This is exactly the same problem as before. What two numbers B and D when multiplied together result in -6, and when added together result in -5?
13)First thing you need to do is calculate the factors of X^2 + 12X + 32: (X + 4)(X + 8).Now the (X + 4)s cancel, leaving you with (X + 8). Answer B.
14)First you need to put “9 - x^2” into standard polynomial form: -x^2 +0X + 9. Now factor it. Using my method from before, A times C must equal -X^2, so one has to equal X and the other has to equal -X. B times D must equal 9. Now BC + AD needs to equal 0X and you know that either A or C is negative, B and D must both equal 3 OR they must both equal -3. So your factors are either (X + 3)(-X + 3) or (X - 3)(-X - 3). Since you’re trying to get rid of the (X - 3) denominator, go with the second set of factors. After canceling the (X - 3) in both the numerator and denominator, you are left with -X - 3. Answer E.