Answer:
vertex = (- 10, - 10 )
Step-by-step explanation:
The equation of a quadratic in vertex form is
y = a(x - h)² + k
where (h, k ) are the coordinates of the vertex and a is a multiplier
To obtain this form use the method of completing the square.
Given
h(x) = x² + 20x + 90
add/subtract ( half the coefficient of the x- term )²
h(x) = x² + 2(10)x + 100 - 100 + 90
= (x + 10)² - 10 ← in vertex form
with (h, k ) = (- 10, - 10 )
A=cost er adult ticket
c=cost per child ticket
2a+14c=96
12a+8c=120
solve
simplify by dividing firs equation by 2 and 2nd by 4
a+7c=48
3a+2c=30
multiply first equaiton by -3 and add to second
-3a-21c=-144
<u>3a+2c=30 +</u>
0a-19c=-114
-19c=-114
divide both sides by -19
x=6
sub back
a+7c=48
6+7c=48
minus 6
7c=42
divide 7
c=6
adult ticket=$6
child ticekt=$6
I think the answer is 2,612.48 because if you multiply the radius, 80 by itself you get 640. Then if you multiply 640 by 3.14 and then multiply the product by 1.3 you get 2,612.48.
