Question

Select one of the factors of x3y2 + 8xy2 - 5x2 - 40.
Can someone help me figure this out?

Answer 1

answer choices
(xy2 + 5)

(x2 + 4)

(xy2 - 5)

(x2 - 8)

Answer 2

Try solving by grouping!
Like so,
x3y2+8xy2-5x2-40
x3y2-5x2+8xy2-40 (rearranged so degree of x is in descending order)
(x3y2-5x2)+(8xy2-40) (Grouping)
x2(xy2-5)+8(xy2-5) (taking out factors)
(x2+8)(xy2-5) (factored)

Check and see if any of those factors match!

Answer 3

i'm still kinda confused on why you rearranged it @NCount

Answer 4

\[x ^{2}(xy ^{2}-5)+8(xy ^{2}-5)=(x ^{2}+8)(xy ^{2}-5)\]

Answer 5

Select one of the factors of 3x2 + 4x - 4.

(x + 4)

(3x + 2)

(3x - 2)

(x - 2)
@neer2890

Answer 6

i'm just having trouble one these

Answer 7

I rearranged it in an order so I could group certain expressions together. Notice how when I pulled out the GCF of both expressions, they yielded the same expression.

Answer 8

\[3x ^{2}+6x-2x-4=0\]
3x(x+2)-2(x+2)=0
(3x-2)(x+2)=0

Answer 9

okay thank you can you help with the other one too? @NCount

Answer 10

Sure thing, yet it seems like neer 2890 beat me too it. :P

What he did there is realized that the 4x could be separated into the 6x and −2x (since when you add them together, they yield 4x) and used the same principle.

Answer 11

thats just confusing to me but i wanna know how to do it instead of just getting the answers...

Answer 12

It definitely takes practice in learning to recognize when to manipulate the problem as such.

Answer 13

yea i know i'm just confused

Answer 14

i still dont get where the 6x and -2x came from @NCount

Answer 15

ok. so you can do this by two methods
1. To find roots of quadratic equation\[ax ^{2}+bx+c=0\]
\[x=\frac{ -b \pm \sqrt{b ^{2}-4ac} }{ 2a }\]

Answer 16

2.in \[ax ^{2}+bx+c=0\]
mutiply ax^2 and c, the value you got then you have to factor that value into two parts such that their addition becomes bx and their multiplication becomes cax^2.,
for e.g.,\[3x ^{2}+4x-4=0\]
mutiply 3x^2 and -4= -4*3x^2=-12x^2
now factor -12x^2 into two parts such that it becomes +4x
i chose 6x and -2x because 6x-2x=4x and 6x*(-2x)=-12x^2