Question

Which of the following show the factored equivalent of f(x)=(x^2-81)(x+5) and it's zeroes

Answer 1

f(x)=(x²-81)(x+5)

we can write 81 as 9²

f(x) =(x²-9²)(x+5)

using the formula a²-b²=(a+b)(a-b)

factored form is:

f(x)=(x+9)(x-9)(x+5)

to find the zeros, f(x)=0 and solve for x

0=(x+9)(x-9)(x+5)

x+9=0, x=-9

x-9=0, x=9

x+5=0, x=-5

zeros are 9, -9 and 5