Write the answer in the form f(a)=b
2006-11-05 13:12:34 · 4 answers · asked by Katy J 1 in Science & Mathematics ➔ Mathematics
f(x) = -2x^2 + 8x - 30
x = (-b)/(2a)
x = (-8)/(2(-2))
x = (-8)/(-4)
x = 2
f(2) = -2(2)^2 + 8(2) - 30
f(2) = -2(4) + 16 - 30
f(2) = -8 - 14
f(2) = -22
ANS :
f(2) = -22
2006-11-05 15:45:08 · answer #1 · answered by Sherman81 6 · 0⤊ 0⤋
f(x) is a formula of a parabola
we have to find co-ordinata of the peak of this parabola whose y is the maximum value of f(x)
x = -b/2a = -8 / 2(-2) = 2
y = -delta / 4a = -( 8^2 - 4(-2)*-(30) ) / 2 * (-2) = -22
f(2) = -22
2006-11-05 21:41:05 · answer #2 · answered by James Chan 4 · 0⤊ 0⤋
f(x)=-2x^2+8x-30
f'(x)=0=-4x+8
x=2
f"(x)=-4 so it is a maximum.
f(2)=-2*2^2+8*2-30=-8+16-30=-22
2006-11-05 21:18:40 · answer #3 · answered by yupchagee 7 · 0⤊ 0⤋
f(x)=-2x^2+8x-30
=-(2x^2-8x+30)
=-2(x^2-4x+10)
=-2(x-2)^2-22
f(2)=-22
2006-11-05 21:21:33 · answer #4 · answered by VanessaM 3 · 0⤊ 0⤋