Been out of school for 5 years and im starting pre pharm in the fall...
2 questions on this sheet i dont understand, please help me. My placement test is tomorrow.

1. Factor Completely:

x^2 - x - 6

a. (x - 2)(x + 3)
b. (x - 1)(x - 6)
c. (x + 2)(x - 3)
d. (x + 1)(x - 6)

Answer is C. Not sure how to get that answer though...


2. Which of the following is the equation of a line that passes through (-2, -1) and (-4, -3)?

a. y= 1/2x + 1
b. y= x + 1
c. y= 1/2x - 1
d y= x - 1

Answer is B. No idea how to even start it...

PLEASE HELP!

1.
If you take (x + 2)(x - 3) = x^2 - x - 6
So step one, take the first side times the other side.
X * X, Which gives us x^2, then X * -3 = -3x
Now take 2 * X = 2x, Then 2* (-3) = -6
Add them all together, x^2 + (-3x) + (2x) + (-6) = x^2 - x - 6

Hope that helped.

1. Consider (x-a)(x-b)
You get x^2-xa-xb+ab
So you have x^2-x-6
So a+b=1
A*b=-6
So use substitution and find a is 3 , b is -2

2. Plug in x=-2 and solve for y, it is -1
Do the same for x=-4 u get y=-3

wow thanks!

There is another one as well...

x^2 -6x + 5 = 0

a. x= -5
b x= -1
c x= 1/5
d x= 5

Answer is D.... But i got B... idk how?

You could always use the guess & check method, or you can separate the algebraic expression into two, expressions as I think they're called that.
If you separate it with common factors, you use (x-a)(x-b).

X is always the same, and you can use the "FOIL" method, which is x times x, then x times b, then a times x, and finally a times b.

You have to figure out which numbers can result in this expression by (x-a)(x-b).

Here, it's (x-5)(x-1) = 0. You find values that can result in this, and the only possible answer on the multiple choices is 5.

Uhm.... lost me lol

There has to be two negatives in this problem, you'll notice that it's positive x^2, then NEGATIVE 6x and then positive 5. When you multiply two negatives, they become positive and because x^2 should be positive it'll be
(x - 5)(x - 1) = x^2 - 5x - 1x + 5 (Do the same thing as above for the previous problem you did) Notice both are negative.

Since you got (x - 5) * (x - 1) = 0 you then find the two things that make this true, by inserting something into x to make it 0.
For this x = 5 because (5 - 5) = 0, the other zero would be x = 1, (1 - 1) = 0

(5 - 5) * (x - 1) = 0 * (x - 1) = 0 (Whatever x - 1 = doesn't matter because it's multiplied by zero anyway)

This post was edited by Trev on Jun 30 2013 05:37pm

I'm not really sure how you explain it as I learned this in middle school so that was a really long time ago.

The format is (x-a)(x-b), at least for the basics, and for this one as well.
Forget about the fact that x^2-6x+5 = 0. Just think of the first part by itself.
You need to factor it out, by means of (x-a)(x-b). X is already the same, you have to see which numbers work out for a and b to get the -6x and 5 part.

Once you get the numbers that works out in (x-a)(x-b) that gets you to x^2-6x+5, you use (x-5)(x-1).

Both parts have X, so you just see which one gets you to 0. Choices would be 5 and/or 1, but as 5 is the only choice, that is the correct answer.