Question

if (x+1) and( x-1) are factor of ax^3+x^2-2x+b , find 'a' and' b'

Answer 1

b-a=-3
b+a=1

b=-1

a=2

......................................................................

Answer 2

Solution:-

given :-

ax^3+x^2-2x+b zeroes are (x+1) and( x-1)

if x = -1 then

a(-1)^3 + (-1)^2-2×(-1)+b= 0

-a +1+2+b = 0

a-b = 3............(1)

if x= 1 then,

a(1)^3+(1)^2 -2×1+b = 0

a +1 -2 +b = 0

a+b = 1.......(2)

additing eq1 ans (2)
________________________

2a = 4

a = 2

put a's value in eq (2)

b = 1-2

b = -1

(a,b)= ( 2,-1) ans