Answer:
5.
x + 2(x + 1) = 8 --> x = 2
y = 2 + 1 = 3
7.
3(9 + 2y) + 5y = 20 --> y = -7/11
x = 9 + 2(-7/11) = 85/11
9.
3(-1 - 2y) + 5y = -1 --> y = -2
x = -1 - 2(-2) = 3
<h2>9.</h2><h3>Given</h3>
<h3>Find</h3>
- linear approximation to the volume when the radius increases 0.4 cm
<h3>Solution</h3>
The equation for volume of a sphere is
... V = (4/3)π·r³
Differentiating gives
... dV = 4π·r²·dr
Filling in the given numbers gives
... change in volume ≈ 4π·(15 cm)²·(0.4 cm)
... = 360π cm³ ≈ 1130.97 cm³ . . . . . . volume of layer 4mm thick
<h2>11.</h2><h3>Given</h3>
- an x by x by 2x cuboid with surface area 129.6 cm²
- rate of change of x is 0.01 cm/s
<h3>Find</h3>
<h3>Solution</h3>
The area is that of two cubes of dimension x joined together. The area of each such cube is 6x², but the two joined faces don't count in the external surface area. Thus the area of the cuboid is 10x².
The volume of the cuboid is that of two cubes joined, so is 2x³. Then the rate of change of volume is
... dV/dt = (d/dt)(2x³) = 6x²·dx/dt
We know x² = A/10, where A is the area of the cuboid, so the rate of change of volume is ...
... dV/dt = (6/10)A·dx/dt = 0.6·(129.6 cm²)(0.01 cm/s)
... dV/dt = 0.7776 cm³/s
The results of the composite functions are:
<h3>What are composite functions?</h3>
Composite functions are functions that are obtained by combining two or more functions together
Assume that:
Then the computation of the composite functions are as follows:
<h3>Function (f * g)(x)</h3>
<h3>Function f(g(x))</h3>
We have: 
This gives
So, we have:
<h3>Function g(f(x))</h3>
We have: 
This gives
So, we have:
Read more about composite functions at:
brainly.com/question/10687170
Answer:
He earns a commission of $66.88.
Step-by-step explanation:
8% of the stereo sale price comes out to 0.08($836.00) = $66.88
He earns a commission of $66.88.
