Question

If f(x)=4x^3+5, then what is the remainder when f(x) is divided by x−3?

Using Remainder theorem

Answer 1

113

Explanation:

Finding a remainder seems like you should be dividing. Remember everything is a shortcut for something else in math. So first you learn Long Division, but that's too much writing, so then you learn Synthetic Division, but there's an even shorter shortcut. It is called Remainder Theorem. If you just substitute 3 (because x-3 in the question) into the function, and you calculate it, you get the remainder.

f(x) = 4x^3 + 5

f(3) = 4(3)^3 + 5

f(3) = 4(27) + 5

= 108 + 5

= 113

See image.