Question

If (x – 1) and (x + 2) are two factors of the polynomial 2x^3 + mx^2 – x – n, then the value of (m^2 – n^2) is

a) -15
b) 9
c) -11
d) 25

Answer 1

Step-by-step explanation:

(x+1) and (x+2) are factors

.: x = -1 or x = -2. -8+12+6a+b

PUT x = -1

.: -1+3+3a+b

.: 2+3a+ b

.: 3a + b = -2 -----------(1)

PUT x = -2

.: -8+12+6a+b

.: 4+6a+b

.: 6a + b = -4 --------------(2)

SUBTRACT (1) FROM (2)

.: 3a = -2

.: a = -2÷3

PUT a = -2÷3 IN (1)

3a + b = -2

.: 3(-2÷3) + b = -2

.: -2 + b =-2

.: b = 0

.: a = -2÷3 and b = 0 is the value of a and b...

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