Question

Verify whether the following are zeroes of the polynomial, indicated against them.
$p\left(x\right)=(x+1)(x-2),x=-1,2$

Answer 1

We know, if $a$ is a zero of $p\left(x\right)$, then $p\left(a\right)=0$.

Given, $p\left(x\right)=(x+1)(x-2)$.

Let $x=-1$:

Then $p(-1)=\left(\right(-1)+1)\left(\right(-1)-2)=0\times (-3)=0$.

That is, $x=-1$ is a zero of the given polynomial $p\left(x\right)$.

Now let $x=2$:

Then $p\left(2\right)=\left(\right(2)+1)\left(\right(2)-2)=3\times 0=0$.

That is, $x=2$ is a zero of the given polynomial $p\left(x\right)$.

Hence, $x=-1,2$ are the zeros of the given polynomial.