Q4 of 64 Page 30

Obtain the value of the following polynomials at the given values of x:

(1) p(x) = 2x3 + 3x2 + 7x + 9 ; at x = 0, 1


(2) p(x) = 3x2 + 10x + 7 ; at x = —3, 1


(3) p(x) = x2 — 2x + 5 ; at x = —1, 5


(4) p(x) = 2x4 — 3x3 + 7x + 5 ; at x = —2, 2

(1) Given, p(x) = 2x3 + 3x2 + 7x + 9


p(0) = 2(0)3 + 3(0)2 + 7(0) + 9


p(0) = 0 + 0 + 9 = 9


p(1) = 2(1)3 + 3(1)2 + 7(1) + 9


p(1) = 2 + 3 + 7 + 9 = 21


(2) Given, p(x) = 3x2 + 10x + 7


p(–3) = 3(–3)2 + 10(–3) + 7


p(–3) = 27 – 30 + 7 = 4


p(1) = 3(1)2 + 10(1) + 7


p(1) = 3 + 10 + 7 = 20


(3) Given, p(x) = x2 — 2x + 5


p(–1) = (–1)2 – 2(–1) + 5


p(–1) = 1 + 2 + 5 = 8


p(5) = (5)2 – 2(5) + 5


p(5) = 25 – 10 + 5 = 20


(4) Given, p(x) = 2x4 — 3x3 + 7x + 5


p(–2) = 2(–2)4 – 3(–2)3 + 7(–2) + 5


p(–2) = 32 + 24 – 14 + 5 = 47


p(2) = 2(2)4 – 3(2)3 + 7(2) + 5


p(2) = 32– 24 + 14 + 5 = 27


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