Question

Answer 1

13) `7a^3-28a=7a(a^2-4)=7a(a-2)(a+2)`

14) `a^3-8a^2+16a=a(a^2-8a+16)=a(a-4)^2`

15) `x^3-8+2x(x-2)=x^3-2^3+2x(x-2)=(x-2)(x^2+2x+4)+2x(x-2)=(x-2)(x^2+4x+4)=(x-2)(x+2)^2`

16) `x^2-49-(7-x)(x+1)=x^2-7^2+(x-7)(x+1)=(x+7)(x-7)+(x+1)(x-7)=(x-7)(2x+8)=2(x+4)(x-7)`

 

Answer 2

13: =7a(a-2)(a+2)

14: \(=a\left(a-4\right)^2\)

15: \(=\left(x-2\right)\left(x^2+2x+4\right)+2x\left(x-2\right)=\left(x-2\right)\left(x+2\right)^2\)

16: \(=\left(x-7\right)\left(x+7\right)+\left(x-7\right)\left(x+1\right)\)

\(=\left(x-7\right)\left(2x+8\right)=2\left(x+4\right)\left(x-7\right)\)