Question

If x+1 is a factor of 2x3 +ax2+2bx +1,then find the values of a and b given that 2a-3b=4

Answer 1

Answer:

x-a=x+1

a= -1

f(x)=f(a)= 2(-1)³ +a-2b+1

        0  =a-2b-1

        a-2b=1 ....eqn1

      2a-3b=4....eqn2

   multiplying eqn1 by 2 and subtracting eqn1 and eqn2 we get,

            2a-4b=2

            2a-3b=4

             (-)  (+) (-)

           b=2

putting the value of b in eqn2 we get,

      2a-3*2=4

       2a=10

       a=10/2 =5