Question

Factor the sum or difference of cubes.

y^3-8

Answer 1

\[\Large a ^{3} - b ^{3} = (a - b)(a ^{2} + ab + b ^{2})\]

Answer 2

is that the final answer?

Answer 3

i dont know how to find b

Answer 4

No that is the identity you will use to factor y^8 - 8
Write y^3 - 8 as y^3 - 2^3 and compare it to the identity. a = y and b = 2

Answer 5

so is it y-2 ....i dont know the second part

Answer 6

Put a = y and b = 2 on the right side of the formula I gave above.

Answer 7

(y-2)(y^2+2y+4)?

Answer 8

did i get it right???^^

Answer 9

Yes.

Answer 10

what do i do for this one: 64n^3-27

Answer 11

do i factor it first?

Answer 12

No. Use the fact that 64 is cube of 4. 27 is cube of 3.

Answer 13

so a = 4 and b=3?

Answer 14

64n^3-27 = (4n)^3 - 3^3
a = 4n and b = 3

Answer 15

wait so do i plug it into the same equation above???

Answer 16

Yes.

Answer 17

I got
(4n-3)(4n^2_12n+9)

Answer 18

No. a = 4n, b = 3. A62 = (4n)^2 = 16n^2, ab = +12n, b^2 = +9

Answer 19

? i dont get it

Answer 20

whats A62???

Answer 21

This is a typo. It should be a^2

a^2 = (4n)^2 = 16n^2, ab = +12n, b^2 = +9

Answer 22

can u please write the answer....ill get it when it is shown...

Answer 23

64n^3-27 = (4n)^3 - 3^3 = (4n - 3)(16n^2 + 12n + 9)

Answer 24

ok how about this one: 2w^3+54

Answer 25

a=2 b=?

Answer 26

Factor the 2 out first.
2w^3+54 = 2(w^3 + 27) = 2(w^3 + 3^3)

Here you have to use a different formula. Previously it was difference of two cubes. Here it is sum of two cubes:\[\Large a ^{3} + b ^{3} = (a + b)(a ^{2} - ab + b ^{2})\]

Answer 27

what does a and b equal?

Answer 28

compare a^3 + b^3 to w^3 + 3^3. You should be able to identify a and b having done two problems already.

Answer 29

2 and 3?

Answer 30

is that it??????

Answer 31

I am sorry. You want answers. But having done two problems you should be able to identify a and b and put it in the formula. I can't keep giving answers for the same problem with just slightly different numbers.