SOLUTION: Given that f(x) = 2x^2 - x + 5 , find a) f(-1) b) f(a+2) Thanks so much in advance:)
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-> SOLUTION: Given that f(x) = 2x^2 - x + 5 , find a) f(-1) b) f(a+2) Thanks so much in advance:)
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Question 836236
:
Given that f(x) = 2x^2 - x + 5 , find
a) f(-1)
b) f(a+2)
Thanks so much in advance:)
Answer by
jim_thompson5910(35256)
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Given that f(x) = 2x^2 - x + 5 , find
a) f(-1)
b) f(a+2)
Thanks so much in advance:)
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a)
Plug in x = -1 and evaluate.
f(x) = 2x^2 - x + 5
f(-1) = 2(-1)^2 - (-1) + 5 ... replace ALL copies of x with -1 (since x = -1)
f(-1) = 2(1) - (-1) + 5
f(-1) = 2 + 1 + 5
f(-1) =
8
-----------------
b)
Plug in x = a+2 and simplify.
f(x) = 2x^2 - x + 5
f(a+2) = 2(a+2)^2 - (a+2) + 5 ... replace ALL copies of x with a+2 (since x = a+2)
f(a+2) = 2(a+2)(a+2) - (a+2) + 5
f(a+2) = 2(a^2+4a+4) - (a+2) + 5
f(a+2) = 2a^2+8a+8 -a-2 + 5
f(a+2) =
2a^2+7a+11
(