Find the value of p for which the quadratic equation (p+1)x2-6(p+1)x+3(p+9)=0 had equal roots , hence find the roots - Maths - Quadratic Equations

Question

Find the value of p for which the quadratic equation
(p+1)x2-6(p+1)x+3(p+9)=0 had equal roots , hence find the roots

Jasmine Kamra · Answer

d = b2-4ac
(6p+6)2 -4(p+1)(3p+27) =0
36p2​+36 +72p -4(3p2 +30p
+27) =0
36p2 +36 +72p-12p2-120p -108 =0
24p2-48p-72 =0
devide by 24
p2-2p-3=0
p2+p-3p-3=0
p(p+1)-3(p+1)=0
(p-3)(p+1)=0
p = 3 or -1