If x=1 is a common root of the equations a x^2 + a x + 3 = 0 and x^2 + x + b = 0, then the value of ab is?

by derpitall

Log in to add a comment

If x=1 is a common root of the equations a x^2 + a x + 3 = 0 and x^2 + x + b = 0, then the value of ab is?

by derpitall

Log in to add a comment

Than, put 1 one the place of x we get,

1^2 + a. 1 + 3 = 0

=>1+a+3 = 0

=>a = -4

Again also, If x=1 is a common root of the equations x^2 + x + b = 0,

Than, put 1 one the place of x we get,

1^2 + 1 + b = 0,

=>1+1+b = 0

=>b=-2

so, ab = (-4)(-2) = 8 (ans)