Question

If x+2and x-3 are factors of 2x³+ax²+bx-18find value of a and b

Answer 1

Answer:

a = 1 , b =-15

Step-by-step explanation:

given 2x^3 +ax^2+bx-18=0--(1)

x+2 is root then x=-2in equation (1)

2(-2)^3 +a(-2)^2 +b(-2) -18=0

4a-2b-34=0

2a-b-17=0---(2)

(x-3) is root then x=3 in equation (1)

2(3)^3 +a(3)^2 +b(3)-18=0

9a+3b+36=0

3a+b+12=0---(3)

by solving equation (2) and (3) we get

5a -5=0

a=1 ,

substitute 'a' value in equation (2)

b = -15