SOLUTION: (2) Given f(x) = 3xsquared - 5x, (a) Find f(-4) (b) Find x if f(x) = 0 (3) Let g(x) = -3(x + 72)squared + 108 (a) Find the zeros of g(x). (b) Identify the axis o

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: (2) Given f(x) = 3xsquared - 5x, (a) Find f(-4) (b) Find x if f(x) = 0 (3) Let g(x) = -3(x + 72)squared + 108 (a) Find the zeros of g(x). (b) Identify the axis o      Log On


   

Question 59085: (2) Given f(x) = 3xsquared - 5x,
(a) Find f(-4)
(b) Find x if f(x) = 0

(3) Let g(x) = -3(x + 72)squared + 108
(a) Find the zeros of g(x).
(b) Identify the axis of symmetry for the graph of g.
Answer by funmath(2933) About Me  (Show Source):
You can put this solution on YOUR website!
(2) Given f%28x%29=3x%5E2-5x,
:
(a) Find f(-4)
f%28-4%29=3%28-4%29%5E2-5%28-4%29
f%28-4%29=3%2816%29%2B20
f%28-4%29=48%2B20
highlight%28f%28-4%29=68%29
:
(b) Find x if f(x) = 0
0=3x%5E2-5x
0=x%283x-5%29
x=0 and 3x-5=0
x=0 and 3x-5%2B5=0%2B5
x=0 and 3x=5
x=0 and 3x%2F3=5%2F3
highlight%28x=0%29 and highlight%28x=5%2F3%29
:
(3) Let g%28x%29=-3%28x%2B72%29%5E2%2B108
:
(a) Find the zeros of g(x).
0=-3%28x%2B72%29%5E2%2B108
-108=-3%28x%2B72%29%5E2%2B108-108
-108=-3%28x%2B72%29%5E2
-108%2F-3=%28x%2B72%29%5E2
36=%28x%2B72%29%5E2
+\-sqrt%2836%29=sqrt%28%28x%2B72%29%5E2%29
+\-6=x%2B72
-72+\-6=x+72-72
x=-72-6 and x=-72%2B6
highlight%28x=-78%29 and highlight%28x=-66%29
:
(b) Identify the axis of symmetry for the graph of g.
g(x) is in vertex form:highlight%28g%28x%29=a%28x-h%29%5E2%2Bk%29, the axis of symmetry is x=h. In your case h=-72, so the axis of symmetry is:
highlight%28x=-72%29
:
Happy Calculating!!!