Saturday 4 February 2017

FUNCTIONS 1B


If f(x) = x4 + kx2 + 7x + 8 has a remainder of 22 when divided by x+2; find k.

solution

f(x) = x4 + kx2 + 7x + 8

x + 2 = 0
x = -2

f(x) = (-2)4 + k(-2)2 + 7(-2) + 8 = 22

16 + 4k + (-14) + 8 = 22

16 + 4k - 6 = 22

16 + 4k = 22 + 6

16 + 4k = 28

4k = 28 - 16

4k = 12

4k = 12
4      4

k = 3

hence k=3

TRY THIS......................


If f(x) = x4 - kx2 + 3x - 8 has a remainder of 30 when divided by x-3; find k.

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