Question

Find the value of a and bif x-1 and x-2 are factors of x-ax+b.​

Answer 1

Correct question:

Find the value of a and bif x-1 and x-2 are factors of x³-ax+b.

Solution:

As x-1 and x-2 are factors of the expression,

x - 1 = 0 and x - 2 = 0 will be its zeroes.

x = 1 and x = 2 are the zeroes of the expression,

Therefore,

1³ - a×1 + b = 0

=> -a + b = -1 —(1)

And,

2³ - a×2 + b = 0

=> - 2a + b = - 8 —(2)

Subtract 2 from 1

-a -(-2a) + b - b = -1 -(-8)

=> a = 8 - 1 = 7

a = 8 - 1 = 7b = -1 + a = 6