Question

Help me with number 5 please! People say it’s simple but it’s not :(

Answer 1

D 7(x^2-2y) (x^2+2y)

Explanation:

7x^4 -28y^2

Factor out 7

7(x^4-4y^2)

This is the difference of squares

a^2 – b^2 = (a + b)(a – b)

let a^2 = x^2 so a=x^2

let b^2 = 4y^2 so b = 2y

7(x^4-4y^2) = 7(x^2-2y) (x^2+2y)