What is the factored form of the expression?

s^4 – 16

a. (s - 2)^2(s + 2)^2

b. (s - 2)(s + 2)

c. (s - i)(s + i)(s - 2)(s + 2)

d. (s - 2i)(s + 2i)(s - 2)(s + 2)

hello from mrbilldoesmath!

answer:

(7 x + 6 y) (49 x^2 - 42 x y + 36 y^2)

discussion:

the trick is to recognize that 343 = 7^3 and 216 = 6^3 and, in general,

a^3 + b^3 =   (a + b) (a^2 - a b + b^2).

in our case

343x^3+216y^3   =   (7x)^3 + (6y)^3

so take a = 7x and b = 6y in the above equation to get the answer.

you,

mrb

you first to choose the points and then move from then as the slope you have