Question

Given ax³+x²+x+b, find the value of a and b if the remainder when divided by (x-1) and (x+1) are 6 & 2

Answer 1

P(1) = 6
a(1)³+(1)²+(1)+b = 6
a+b+2 = 6
a+b = 4 -(1) < what's this -1 for ?

P(-1) = 2
a(-1)³+(-1)²+(-1)+b = 6
-a + b -2= 6
-a + b = 8 -(2) < what's this -2 for ?

Answer 2

It's not -1 and it's not -2
a+b = 4 -(1)
=> called a+b = 4 as equation (1)
Similarly,
-a + b = 8 -(2)
=> called -a+b = 8 as equation (2)

Answer 3

Ohhhh ! alright

Answer 4

do i make (1) = (2) now ?

Answer 5

@Callisto

Answer 6

Nope, not really. Solve:
a+b = 4 -(1)
-a + b = 8 -(2)

(1) + (2)
What do you get?

Answer 7

b=-2

Answer 8

How did you get that?