Question

x-1=15/x+1 by use formula x-b±squre rootb-4ac/2a

Answer 1

Given equation,

$\sf{x - 1 = \frac{15}{x + 1} }$

Converting into the general form of a Quadratic Equation,

$\sf{x {}^{2} - 1 {}^{2} = 15 } \\ \\ \implies \: \sf{x {}^{2} - 16 = 0}$

On comparing with ax²+bx+c=0,

Here,a=1,b=0 and c= -16

Discriminant of the equation,

D=b²-4ac

→D=(0)²-4(1)(-16)

→D=64

On putting the values in quadratic formula,

$\sf{x = \frac{ - b \pm \sqrt{d} }{2a} } \\ \\ \implies \: \sf{x = \frac{ \pm8}{2} } \: \\ \\ \implies \: \sf{x = \pm 4 }$