Question

if x+1 is factor of polynomial 2x3+ax2+2bx+1 then find value a ND b given that 2a-3b=4

Answer 1

As X + 1 = 0
X = - 1
Now put the X value in equation
2(-1)(-1)(-1) + a(-1)(-1) + 2b(-1) + 1 = 0
-2 + a - 2b + 1 = 0
a - 2b - 1 = 0
a - 2b = 1 ............. (1)
2a - 3b = 4 ............... (2) given in Q
Multiply (1) by 2 & then sub
2a - 4 b = 2
2a - 3b = 4
- + -
_________________________
- b = - 2
b = 2
Subsitute b value in (2)
2a - 3x2 = 4
2a - 6 = 4
2a = 4 + 6
2a = 10
a = 5