SOLUTION: f(x)=-16x^2+8x+3 The vertex is (1/4,4) and it opens downward. I need help determing the x and y intercepts. I have graphed it using the graphing solver but every answer I com

Algebra ->  Graphs -> SOLUTION: f(x)=-16x^2+8x+3 The vertex is (1/4,4) and it opens downward. I need help determing the x and y intercepts. I have graphed it using the graphing solver but every answer I com      Log On


   

Question 371956: f(x)=-16x^2+8x+3
The vertex is (1/4,4) and it opens downward.
I need help determing the x and y intercepts. I have graphed it using the graphing solver but every answer I come up with it wrong.
Found 2 solutions by Fombitz, ewatrrr:
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
y-intercept: Set x=0 and solve for y
y=f%280%29=0%2B0%2B3=3
(0,3)
.
.
.
x-intercept: Use the vertex form.
-16%28x-1%2F4%29%5E2%2B4=0
16%28x-1%2F4%29%5E2=4
%28x-1%2F4%29%5E2=1%2F4
x-1%2F4=0+%2B-+1%2F2
x=1%2F4+%2B-+1%2F2
x=3%2F4 and x=-1%2F4
.
.
(3%2F4,0) and (-1%2F4,0)

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi,

f(x)=-16x^2+8x+3

f(x)=-16[x^2+(1/2)x -3/16}

f(x)=-16[(x-1/4)^2 - 1/16 -3/16}

f(x)=-16(x-1/4)^2 + 4

x intercepts (y=0)

0 = -16(x-1/4)^2 + 4

-4/-16 = (x-1/4)^2  taking the square root of both sides of the equation

+-2/4 = x - 1/4

1/4 +- 1/2 = x

-1/4 = x

3/4 = x

y intercept (x=0)

y = -16(-1/4)^2 + 4

y = -1 + 4 = 3