Factor completely
x^2+13x+40
the answer is (x+8)(x-5)
Please show work so I can make sure that I factored this correctly Thank YOU!
2007-12-02 06:00:28 · 12 answers · asked by tbond_1969 1 in Science & Mathematics ➔ Mathematics
Step 1
Factors of x² are x and x
(x******)(x******)
Step 2
Find factors of 40 that can be combined with factors in Step 1 to give a product of 40 and a sum of 13
(x*****8) (x*****5)
Step 3
Insert + or - signs
(x + 8)(x + 5)
Check
x² + 5x + 8x + 40
x² + 13x + 40 (as required)
2007-12-02 06:11:13 · answer #1 · answered by Como 7 · 3⤊ 1⤋
list out the factors of 40 and add them
40 = 1x40; 40+1 = 41
= 2x20;2+20 = 22
= 4x10; 4+10 = 14
=5x8; 5+8 = 13 which equals to the coeff of x
use that for the factoring
(x+8)(x+5)
use foil to check
x^2 +5x + 8x + 40 = x^2 + 13x + 40
2007-12-02 06:05:08 · answer #2 · answered by norman 7 · 1⤊ 1⤋
Nope, not quite
Ways to tell:
You can FOIL it, and it comes out the same.
Put x=2 in for both equations to see if it's the same.
OR
check your work.
Factors of 40 that add to 13:
1+40=41 (Doesn't work)
2+20=22 (Doesn't work)
4+10=14 (Doesn't work)
5+8=13 Yay! We found our answer. So now we need to plug it into a factored equation: (x+5) (x+8)
2007-12-02 06:08:30 · answer #3 · answered by Jasmine 4 · 0⤊ 1⤋
(x+5)(x+8)
2007-12-02 06:04:19 · answer #4 · answered by dwinbaycity 5 · 1⤊ 0⤋
x^2+13x+40
sum= 13
product= 40
(x+8)(x+5)
USING FOIL:
x *x= x^2
8x+5x= 13x
8 * 5= 40
So the correct answer is (x+8)(x+5) not (x+8)(x-5)
just remember to foil!
2007-12-02 06:06:47 · answer #5 · answered by Kelly 2 · 0⤊ 1⤋
that's not the answer.
It's (x+8)(x+5)
I'll assume that's a typo though.
You have an X^2 and two +'s, so your answer will be in the form:
(x+?)(x+?)
Those ?'s are figured out like this:
What two numbers multiplied together equal 40 and added together equal 13? 8 and 5.
There you go.
2007-12-02 06:04:20 · answer #6 · answered by mazdamandan 4 · 1⤊ 1⤋
It should be + on both of your factors =) When the last sign is positive it means both factors are gonna be the same in whatever the first sign is. If you know how to foil, i would do that if your unsure bc that shows you the original problem.
F first O outside I inside L last
2007-12-02 07:01:47 · answer #7 · answered by harmonieclark 4 · 0⤊ 2⤋
lol your answer is wrong
this is the answer
(x+5)(x+8)
there is really any working out, you need to find two numbers that add up to +13 and mutiply to get +40 and ther are +8 and +5
2007-12-02 06:03:56 · answer #8 · answered by wag1 2 · 2⤊ 2⤋
i think it's (x+8)(x+5):
product: 40
sum: 13
the numbers that fit are 8 and 5....
so...
(x+8)(x+5)
or you can do decomposition:
product: 40
sum: 13
x^2 + 8x + 5x+ 40
x(x+8) + 5(x+8)
soo....
(x+8)(x+5)
hope that helps :)
2007-12-02 06:08:45 · answer #9 · answered by Tofuie 3 · 0⤊ 1⤋
(x+5)(x+8) is the correct answer.
2007-12-02 06:03:26 · answer #10 · answered by ironduke8159 7 · 4⤊ 0⤋