Evaluate the expression 2ab^3 + 6a^3 - 4ab^2 when a = 2 and b = 4.

The measurenicnt of the circumference of a circle is found to be 56 centimeters. The possible error in measuring the circumferen

BartSMP [9]

Answer:

(a) Approximate the percent error in computing the area of the circle: 4.5%

(b) Estimate the maximum allowable percent error in measuring the circumference if the error in computing the area cannot exceed 3%: 0.6 cm

Step-by-step explanation:

(a)

First we need to calculate the radius from the circumference:

$c=2\pi r\\r=\frac{c}{2\pi } \\c=8.9 cm$

I leave only one decimal as we need to keep significative figures

Now we proceed to calculate the error for the radius:

$\Delta r=\frac{dt}{dc} \Delta c\\\\\frac{dt}{dc} = \frac{1}{2 \pi } \\\\\Delta r=\frac{1}{2 \pi } (1.2)\\\\\Delta r= 0.2 cm$

$r = 8.9 \pm 0.2 cm$

Again only one decimal because the significative figures

Now that we have the radius, we can calculate the area and the error:

$A=\pi r^{2}\\A=249 cm^{2}$

Then we calculate the error:

$\Delta A= (\frac{dA}{dr} ) \Delta r\\\\\Delta A= 2\pi r \Delta r\\\\\Delta A= 11.2 cm^{2}$

$A=249 \pm 11.2 cm^{2}$

Now we proceed to calculate the percent error:

$\%e =\frac{\Delta A}{A} *100\\\\\%e =\frac{11.2}{249} *100\\\\\%e =4.5\%$

(b)

With the previous values and equations, now we set our error in 3%, so we just go back changing the values:

$\%e =\frac{\Delta A}{A} *100\\\\3\%=\frac{\Delta A}{249} *100\\\\\Delta A =7.5 cm^{2}$

Now we calculate the error for the radius:

$\Delta r= \frac{\Delta A}{2 \pi r}\\\\\Delta r= \frac{7.5}{2 \pi 8.9}\\\\\Delta r= 0.1 cm$

Now we proceed with the error for the circumference:

$\Delta c= \frac{\Delta r}{\frac{1}{2\pi }} = 2\pi \Delta r\\\\\Delta c= 2\pi 0.1\\\\\Delta c= 0.6 cm$

5 0

3 years ago

The sum of a number and 7 is less than 12

Hitman42 [59]

5
explanation:
12-7=5

6 0

3 years ago

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What is the value of A?

Artemon [7]

Answer:

101

Step-by-step explanation:

The theorem to use this is the intercepted arc theorem, which tells us that if we take 2 points on the circumference of a circle and create an angle in the opposite side of the circumference, that angle is HALF that of the ARC intercepted.

If we look at 100 degree angle, we see the ARC intercepted is 99 degree and a degrees. According to theorem, we can say:

99 + a = 2(100)

99 + a = 200

a = 200 - 99

a = 101

6 0

3 years ago

What is the value of the expression below when z =5 and w=5? 9z-3w

zysi [14]

This is just about substitution!! 9(5)-3(5), 3 • 5 = 15
9 • 5 = 45
so Now you have, 45 - 15 = 30

7 0

2 years ago

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6x/5 - x = x/15 - 10/3

Vadim26 [7]

Answer:

x=-25

6x/5 - x = x/15 - 10/3

x/5 = x/15 - 10/3

3x = x - 50

3x - x = -50

2x = -50

x = -50/2

X=-25

4 0

2 years ago

Read 2 more answers