when a polynomial 2 x cube + 3 X square + a x + b is divided by x minus 2 leaves remainder 2 and X + 2 leaves remainder minus 2 then find a and b
Answers
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Answer:
Value of a is -7 and Value of b is -12
Step-by-step explanation:
Given polynomial:
p(x) = 2x³ + 3x² + ax + b
To find: Value of a and b
We use remainder theorem to form 2 equation in 2 variable.
Remainder Theorem states that if a polynomial oh any degree say q(x) is divided by a linear polynomial of form x - b then the remainder = q(b).
So,
when p(x) is divided by x - 2 ,
Remainder = 2
p(2) = 2
2(2)³ + 3(2)² + a(2) + b = 2
16 + 12 + 2a + b = 2
2a + b = 2 - 28
2a + b = -26 ...............................(1)
when p(x) is divided by x + 2 ,
Remainder = -2
p(-2) = -2
2(-2)³ + 3(-2)² + a(-2) + b = -2
-16 + 12 - 2a + b = -2
-2a + b = -2 + 4
-2a + b = 2 ...............................(2)
Add (1) and (2)
b + b = -26 + 2
2b = -24
b = -12
Put value of b in (1)
2a + (-12) = -26
2a = -26 + 12
2a = -14
a = -7
Therefore, Value of a is -7 and Value of b is -12