Area of a square = length²
A = x²
16 = x²; x = 4
dA/dx = 2x cm²/s
dx/dt = 6 cm/s
Using chain rule:
dA/dt = dA/dx * dx/dt
dA/dt = 2x * 6
dA/dt = 12x
At x = 4,
dA/dt = 12(4) = 48 cm²/s
Answer:
She is paid $6.25.hour at the concession and $8.50 as a lifeguard.
Step-by-step explanation:
We know:
18 hours as a lifeguard
12 hours at concession
Total earned = $228
18L + 12C = 228
Then:
24 hours as a lifeguard
8 hours at concession
Total earned = $254
24L + 8C = 254
Move one equation around to get one variable by itself: in this case we can solve for L:
18L + 12C = 228
18L = 228 - 12C
L = (228/18) - (12/18)C
Plug in for L:
24((228/18) - (12/18)C) + 8C = 254
Solve for C:
C = 6.25
Now that we know C, plug in value for C and solve for L:
18L + 12(6.25) = 228
L = 8.5
So she is paid $6.25.hour at the concession and $8.50 as a lifeguard.
Step OneUse the vertex to determine the basic equation for the parabola.
y = a(x - 2)^2 + 7 Notice the sign change for x. I have provided a graph to show how this would look with a = 1 (in red.)
What it means is the 2 has to be minus in order that the vertex will shift 2 units in the x direction.
Step TwoUse the point to solve for a.
y = a(x - 2)^2 + 7
When x = - 1
Then y = 3
3 = a(-1 - 2)^2 + 7 combine -1 with - 2
3 = a (-3)^2 + 7
3 = 9a + 7 Subtract 7 from both sides
3 - 7 = 9a
-4 = 9a Divide by 9.
a = -4/9
or
a = - 0.4444
y = -0.4444(x + 2)^2 + 7 <<<<<
answer
y = - 4/9 (x + 2)^2 + 7
Note: if you have choices, list them please.
Note: The red graph is y = (x - 2)^2 + 7 ; a = 1
The blue graph is y = - 4/9(x - 2)^2 + 7 ; a = - 0.44444
You should notice that the a does 3 things to the graph. Before you read the answer, what are those three things? The answer is in the comments.
61•bcThe answer to this question