Question

How do you solve this?

Answer 1

`image`

Answer 2

Note that 125 = 5³. Make use of the factorization of the sum of cubes:

a³ +b³ = (a+b)(a² -ab +b²) . . . . . . a formula worth keeping handy

Then ...

`(x^3+5^3)/(x+5)=((x+5)(x^2-5x+5^2))/(x+5)=x^2-5x+25`

_____

When x=-5, this evaluates to

... (-5)²-5(-5) +25 = 75