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3 years ago

5x + 7y = 25 5x - 2y = -65 solve using elimination (step by step please)

Mathematics

1 answer:

aliina [53]3 years ago

6 0

5x+7y=25

5x-2y=-65

subtract both of the equations

5x-5x=0

7y--2y= 7y+2y=9y

25--65=25+65=90

0+9y=90

9y=90

divide both sides by 9 to get y by itself

9y/9=90/9

cross out 9 and 9 which becomes 1*1*y=y

90/9=10

y=10

find x by using the substitution method

5x+7y=25

5x+7(10)=25

5x+70=25

move +70 to the other side

sign changes from +70 to -70

5x+70-70=25-70

5x=-45

divide both sides by 5 to get x by itself

5x/5=-45/5

cross out 5 and 5 then becomes 1*1*x=x

-45/5=-9

x=-9

answer:

(-9,10)

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By the Exterior Angle Theorem, we know that the exterior angle is equal to the sum of the two opposite interior angles.

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3 years ago

A cone has a volume of 3533.5 cubic inches and a radius of 15 inches. What is its height?

tia_tia [17]

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Step-by-step explanation:

1. The formula of the volume is:

V= $\frac{ab(h)}{3}$

2. So you have to substitute the the data that you have:

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3. To have the area of the base (ab) you have to get the formula of the circle's area and solve:

A= $\pi$ ( $r^{2}$ )

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4. Now you have the area of the base:

3533.5 $in^{3}$ = $\frac{706.86(h)}{3}$

5. In this step you are going to clear the variable which is the heigh (h) and solve as an equation:

3533.5 $in^{3}$ = $\frac{706.86(h)}{3}$

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The result may vary depending on the value of $\pi$ that you use,

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