Question

Solve the equation using formula. $9x+1=4x^2$

• A. $x=\frac{9\pm \sqrt{97}}{8}$
• B. $x=\frac{-9\pm \sqrt{97}}{8}$
• C. $x=\frac{9\pm \sqrt{55}}{8}$
• D. $x=\frac{-9\pm \sqrt{55}}{8}$

Answer 1

The correct option is A $x=\frac{9\pm \sqrt{97}}{8}$

Given equation is:

$4x^2-9x-1=0$

Applying quadratic formula,
$x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$

$a=4,b=-9,c=-1$

$\therefore x=\frac{9\pm \sqrt{81-4(-1)\left(4\right)}}{2\times 4}$

$\therefore x=\frac{9\pm \sqrt{97}}{8}$