Answer:
9.5 inches
Step-by-step explanation:
The relationship is presumed to be ...
(first week's growth) + (second week's growth) = (growth in two weeks)
(first week's growth) + 3.43 inches = 12.93 inches . . . . . fill in the numbers
Subtract 3.43 from both sides of the equation:
first week's growth = 12.93 inches - 3.43 inches
first week's growth = 9.50 inches
The plant grew 9.50 inches in the first week.
Answer:
S'(x)=-0.006x2+0.8x+9
Step-by-step explanation:
The rate of change of the sales S(x) with respect to the amount of money spent on advertising x is then the derivative of S(x) with respect to x. What we have to calculate is S'(x).
We know that the derivative of 
is 
(where a is a constant), and the derivative of a sum is the sum of the derivatives, so we can calculate the derivative of each term independently:
S'(x)=(−0.002x3 + 0.4x2 + 9x + 500)'=(−0.002)(3)x2 + (0.4)(2)x + 9
Which means:
S'(x)=-0.006x2+0.8x+9
Solve for x in 2x + 2y = 6
x = 3 - y
Substitute x = 3 - y into 3x - 5y = 25
9 - 8y = 25
Solve for y in 9 - 8y = 25
y = -2
Substitute y = -2 into x = 3 - y
x = 5
Thus,
<u>y = 5</u>
<u>y = -2</u>
