Question

Let $f$ be a function such that $f$ : $x\to 2x^2+3$. Then $f\left(2\right)+f(-2)=$

Answer 1

Given, $f\left(x\right)=2x^2+3$

$f\left(1\right)=2(1{)}^2+3=2(1)+3=2+3=5$
$f\left(2\right)=2(2{)}^2+3=2(4)+3=8+3=11$
$f\left(3\right)=2(3{)}^2+3=2(9)+3=18+3=21$
Now, $f\left(1\right)+f\left(2\right)=5+11=16$ which is not equal to $f\left(3\right)$.
Also $f(-2)=2\left({(-2)}^2\right)+3=2\left(4\right)+3=8+3=11$.
Thus, the value of $f\left(2\right)+f(-2)=11+11=22$ is not equal to $0$.