Question

Can someone help me figure this out?

Select one of the factors of x^2 – 17x + 72

I will leave the possible answers here as reference:
a)x - 8
b)x - 2
c)x + 9
d)x + 12

I am taking Algebra 2 and am currently pulling a high "B". I want to bring that up to an "A". Can anyone explain the steps I need to figure this out? :D

Answer 1

(x-8)(x-9)

Answer 2

How did you figure that out?

Answer 3

You should two numbers whose product is 72
And whose sum is 17

Answer 4

*find

Answer 5

x^2-17x+72=0
x^2-8x-9x+72=0
x(x-8)-9(x-8)=0
(x-8)(x-9)=0

Answer 6

Alright, that makes sense. Thanks! I just got the same answer! Thank you so much!

Answer 7

Ok, so I have this problem now which is 4x^2 - 8x - 140.

A) x + 5
B) 8
C) x - 4
D) x - 2

I tried getting the answer by finding two numbers that get the product of -140 and the sum of -8. I ended up with (x + 5)(x - 13) so that would give me -8 but not a product of -140.

I am hopelessly confused, can anyone clear this up for me?

Answer 8

You can simplify that by taking out the common factor "4"

Answer 9

So, it would end up being 4(x + y)(x + y)

Answer 10

y being a placeholder

Answer 11

Divide through out by 4
you get
x^2-2x-35=0
x^2-7x+5x-35=0
X(x-7)-5(x-7)=0
(x-7)(x-5)=0

Answer 12

yeah but first find what the quad equation would look like

Answer 13

*x+5

Answer 14

Factoring equations sucks.. :(

Answer 15

scasm already did the work for you though

Answer 16

I see that, I was trying to figure it out so I didn't have to keep asking for help. :P

Answer 17

you'll eventually get used to it :)) its really frustrating at first you know

Answer 18

Alright, I think this will be the last question I need to understand it.
2x^2 + 16x - 18

I factored out the common factor which is 2.

so now I have x^2 + 8x - 9

I imagine the quad would be x^2 + 4x + 4x - 9.

what can I do from here or what did I do wrong?

Answer 19

You dont get 4 and 4. Since the last number is 9, u have this
with some permutations and combinations get two numbers such that their product is 9 and their sum is 8. Here 3*3*1 are factors of 9 .So its 9 and 1
equation will be x^2+9x-x-9=0 Here the product should be -9 as indicated by the equation, so the factors are 9 and -1 which also complies with their sum 9-1=8 which is right in the middle of the eqn