Question

Solve $x^2-7x+12=0$ by formula method.

Answer 1

Given $x^2-7x+12=0$
This is in the form $a{x}^2+bx+c=0$ where, a = 1, b = -7 and c = 12
Quadratic formula is, $x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$
By substituting the values, we get
$x=\frac{-(-7)\pm \sqrt{(-7{)}^2-4\times 1\times 12}}{2\times 1}=\frac{7\pm \sqrt{49-48}}{2}=\frac{7\pm \sqrt{1}}{2}=\frac{7\pm 1}{2}$
If $x=\frac{7+1}{2}=\frac{8}{2}=4$ $x=\frac{7-1}{2}=\frac{6}{2}=3$
$\therefore$ 4 and 3 are the roots of $x^2-7x+12=0$