Question:
The root of a quadratic equation are 5 and −2. Then, the equation is
(a) $x^{2}-3 x+10=0$
(b) $x^{2}-3 x-10=0$
(c) $x^{2}+3 x-10=0$
(d) $x^{2}+3 x+10=0$
Solution:
(b) $x^{2}-3 x-10=0$
It is given that the roots of the quadratic equation are 5 and $-2$.
Then, the equation is:
$x^{2}-(5-2) x+5 \times(-2)=0$
$\Rightarrow x^{2}-3 x-10=0$