Question

The solution set of the quadratic equation $x^2-30x+221=0$ is

• A. $\{13,17\}$
• B. $\{-13,-17\}$
• C. $\{-13,17\}$
• D. $\{13,-17\}$

Answer 1

The correct option is A $\{13,17\}$

$x^2-30x+221=0$

$\Rightarrow x^2-17x-13x+221=0$

$\Rightarrow x(x-17)-13(x-17)=0$

$\Rightarrow (x-17)(x-13)=0$

$\therefore x-17=0$ or $x-13=0$

$\therefore x=17$ or $x=13$

$\therefore$ The solution set is $\{13,17\}$