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2 years ago

What system of equations would you use to solve the problem below?

Mathematics

1 answer:

EleoNora [17]2 years ago

4 0

Let x be multiple-choice questions
Let y be short-answer questions

x + y = 28

3x + 5y = 100

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Solve a system of equation by elimination

maks197457 [2]

Answer:

1: (4,1) x=4 y=1

2: (1,10) x=1 y=10

3: (-25/4,5) x= -25/4 y=5

Step-by-step explanation:

It would be a lot to explain all three so if you really need it just ask

6 0

3 years ago

Using the 0,1,6,8, and 9, write down all the possible three-digit numbers that have rotational symmetry. the digits can be used

Hunter-Best [27]

Assuming 1 is written rotationally symmetrical, using 0,1,6,8,9 to make numbers that have a degree of symmetry of 2 (i.e. 180 degrees), we can say

one digit numbers: 0,1,8

two digit numbers: 11, 69, 96

(18 becomes 81, so not admissible, similarly for 19, 91,16,61, etc)

(00 is not considered generally as a two-digit number)

three digit numbers:

(000, 010, 080 are not considered generally as a three-digit number)

101, 609, 808, 906,

replace the middle digit successively by 1 and 8 gives

111, 619, 818, 916,

181, 689, 888, 986

for a total of 12 numbers

4 0

3 years ago

The circumference of a sphere was measured to be 80 cm with a possible error of 0.5 cm. A) Use differentials to estimate the max

siniylev [52]

Answer:

A) The maximum error in the calculated surface area: $25cm^2$

Relative error: $0.013$

B) The maximum error in the calculated volume: $162cm^2$

Relative error: $0.019$

Step-by-step explanation:

A) The formula for the surface area is:

$A=4\pi r^2$

The measured value is the circumference which is equal to:

$C=2\pi r$

then the radius is:

$r=\frac{C}{2\pi}$

Substituting in the formula of the surface:

$A=4\pi(\frac{C}{2\pi})^2\\A=4\pi(\frac{C^2}{4\pi^2})\\A=\frac{C^2}{\pi}$

Using the formula to calculate the error:

$dy=f'(x)dx$

Where $x$ is the variable measured and $y$ is a function of $x$ ( $y=f(x)$ ).

$dA=f'(C)dC\\dA=\frac{2C^{(2-1)}}{\pi}dC\\dA=\frac{2C}{\pi}dC$

We have C=80cm and dC=0.5cm

$dA=\frac{2C}{\pi}dC\\dA=\frac{2(80)}{\pi}(0.5)\\dA=\frac{160}{\pi}(0.5)\\dA=50.9296(0.5)\\dA=25.4648\approx25cm^2$

The relative error is the maximum error divide by the total area. The total area is: $A=\frac{C^2}{\pi}=\frac{(80)^2}{\pi}=\frac{6400}{\pi}=2037.1833cm^2$

$\frac{dA}{A}=\frac{25.4648}{2037.1833} =0.0125\approx0.013$

B) The formula for the volume is:

$V=\frac{4}{3} \pi r^3$

Using $r=\frac{C}{2\pi}$

$V=\frac{4}{3} \pi r^3\\V=\frac{4}{3} \pi (\frac{C}{2\pi})^3\\V=\frac{4}{3} \pi (\frac{C^3}{8\pi^3})\\V=\frac{1}{3}(\frac{C^3}{2\pi^2})\\V=\frac{C^3}{6\pi^2}$

The maximum error is:

$dV=\frac{3C^{3-1}}{6\pi^2}dC\\dV=\frac{C^{2}}{2\pi^2}dC\\dV=\frac{(80)^{2}}{2\pi^2}(0.5)\\dV=\frac{6400}{2\pi^2}(0.5)\\dV=\frac{6400}{2\pi^2}(0.5)\\dV=(324.2278)(0.5)\\dV=162.1139\approx162cm^2$