Question

If 4 is the root of quadratic equation x²+ax-8=0 then a=

Answer 1

4^2+4a-8=0
16+4a-8=0
4a=-8
a=-2

Answer 2

putting value of x in given eqn
we get
4^2+a4-8=0
16+4a-8=0
4a=8-16
a=-8/4=-2