Sum
The polynomials 2x3 – 7x2 + ax – 6 and x3 – 8x2 + (2a + 1)x – 16 leaves the same remainder when divided by x – 2. Find the value of ‘a’.
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Solution
Lef f(x)=`2x^3-7x^2+ax-6`
x-2=0 ⇒ x=2
When f (x) is divided by (x-2), remainder = f(2)
∴ `f(2)=2(2)^3-7(2)^2+a(2)-6`
=`16-28-2a-6`
= 2a-18
Let `g(x)=x^3-8x^2+(2a+1)x-16`
When g (x) is dividend by (x-2), remainder=g(2)
∴ `g(2)=(2)^3-8(2)^2+(2a+1)(2)-16`
= 8-32+4a+2-16
= 4a-38
By the given condition, we have:
f(2)=g(2)
2a-18=4a-38
4a-2a=38-18
2a=20
a=10
Thus, the value of a is 10
Concept: Remainder Theorem
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