Question

What are the zeroes of the function, f(x) = x^2 - 2x - 15?
(1) {3,5}
(2) {-3,5}
(3) {-5, 3}
(4) {-5 , -3}

Answer 1

In this case, we make f(x) to zero, and guess and check right?

Answer 2

set the f(x)=0, and solve for x.

\(\Large\color{blue}{ \rm x^2 - 2x - 15=0 }\)
\(\Large\color{blue}{ \rm (x+3)(x-5)=0 }\)
\(\Large\color{blue}{ \rm x=~? }\)

Answer 3

Oh yah. That's much easier than guessing and checking. Thanks!~