Question

Find the zeroes of the quadratic polynomial:
4x2 — x — 5

Answer 1

$\blue{\bold{\underline{\underline{Answer:}}}}$

$\green{\tt{\therefore{Value\:of\:x=-1\:and\:\frac{5}{4}}}}$

$\orange{\bold{\underline{\underline{Step-by-step\:explanation:}}}}$

$\green{\underline \bold{Given :}} \\ \tt: \implies {4x}^{2} - x - 5 = 0 \\ \\ \red{\underline \bold{To \: Find :}} \\ \tt: \implies Value \: of \: x = ?$

• According to given question :

$\bold{As \: we \: know \: that} \\\tt: \implies {4x}^{2} -x -5 = 0 \\ \\ \tt: \implies {4x}^{2} +4x - 5x -5 = 0 \\ \\ \tt: \implies 4x(x + 1) - 5(x + 1) = 0 \\ \\ \tt: \implies(4x -5)(x + 1) = 0\\ \\ \green{\tt: \implies x = - 1 \: and \: \frac{ 5}{4}} \\ \\ \bold{Alernate \: method} \\ \tt: \implies x = \frac{ - b \pm \sqrt{ {b}^{2} - 4ac} }{2a} \\ \\ \tt: \implies x = \frac{ - (-1) \pm \sqrt{ {1}^{2} - 4 \times 4 \times (-5) } }{2 \times 4} \\ \\ \tt: \implies x = \frac{ 1 \pm \sqrt{81} }{8} \\ \\ \tt: \implies x = \frac{ 1 \pm9}{8} \\ \\ \green{\tt: \implies x = - 1 \: and \: \frac{5}{4} }$

Answer 2

$\large \underline{ \blue{ \boxed{ \bf \green{Required \: Answer}}}}$