Question

If one root of the equation x²+ax+8=0 is 4 while the equation x²+ax+b=0 has equal roots , find b.

Answer 1

Step-by-step explanation:

4^2+a*4+8=0

a=-6

x2-6x+b=0 has equal roots

b2-4ac=0

36_4*1*b=0

b=9

Answer 2

Answer:

9

step by step:

x^2+ax+8=0,where 4is one of the roots

so f(4)=0

=16+4a+8=0

24+4a=0

a=-6

x^2+ax+b have equal roots

so x^2-6x+b have equal roots

if any quadratic equation have equal roots then the roots are -b/2a

here b=-6;a=1

roots are 3,3

a quadratic equation having roots m, n is x^2-(m+n)x+mn=0

here both m and n are 3

so the quadratic equation is x^2-6x+9

so b=9