If f(x)= 2x cubed + Ax squared + 4x -5 & f(2)=5,what is the value if A?

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2007-09-22 14:46:00 · 4 answers · asked by Anne Marie W 1 in Science & Mathematics ➔ Mathematics

f(x) = 2x^2 + Ax^2 + 4x - 5
f(2) = 5 = 2*2^3 + A*2^2 + 4*2 - 5
5 = 16 + 4A + 8 - 5

2007-09-22 14:50:43 · answer #1 · answered by Raymond 7 · 0⤊ 0⤋

Just plug the values in the equation. So:
5 = 2*2^3 + A*2^2 + 4*2 - 5
so 10 = 24 + 4A
so A = -14/4 = -7/2
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2007-09-22 21:53:54 · answer #2 · answered by tsr21 6 · 0⤊ 0⤋

f(x) = 2x^2 + Ax^2 + 4x - 5
f(2) = 2*2^3 + A*2^2 + 4*2 – 5 = 5
0 = 16 + 4A + 8
-4A = 16 + 8 = 24
A = -6

2007-09-22 22:07:30 · answer #3 · answered by Cider Sid 1 · 0⤊ 0⤋

for the function, plug in 2 for x and 5 for f(x)

5=2(2)^3+A(2)^2+4(2)-5
5=16+4A+3
-14=4A
A=-7/2

2007-09-22 21:51:06 · answer #4 · answered by Q 2 · 1⤊ 0⤋