 #1
 112
 5
Homework Statement
2. Homework Equations
The Attempt at a Solution
a) [/B]f(x) = 5x^{2} + 20x + 2
y = 5x^{2} + 20x + 2
Factor 5 from the first two terms:
y = 5x^{2} + 20x + 2
= 5 (x^{2} – 4x) +2
Complete the square in the bracket:
(1/2 b)2 = [1/2 (4)]2 = (2)^{2} = 4
Group the perfect square trinomial:
= 5 (x^{2} – 4x + 4 – 4) +2
Remove 4 from the brackets, it must be multiplied by 5:
= 5 [(x^{2} – 4x + 4) – 4] +2
=  5 (x^{2} – 4x + 4) + 20 + 2
Factor the trinomial. Add remaining constants:
= 5 (x2)^{2} + 22
b) The vertex is (2, 22)
c) Since the parabola is concave down, the maximum value is y = 22
d)f(x) = 5x^{2} + 20x + 2
y = 5x^{2} + 20x + 2
Let y = 0
0 = 5x^{2} + 20x + 2
Substitute a = 5, b = 20, c = 2 into the quadratic formula:
The xintercepts are x= 0.09 and x = 4.09
Is this correct?
Thanks.
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