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alexandr402 [8]
3 years ago
11

Find the solution of this system of equations. x-8y=21 and 3x-8y=15

Mathematics
1 answer:
dusya [7]3 years ago
8 0

Answer:

x = -3 , y = -3

Step-by-step explanation:

Solve the following system:

{x - 8 y = 21 | (equation 1)

3 x - 8 y = 15 | (equation 2)

Swap equation 1 with equation 2:

{3 x - 8 y = 15 | (equation 1)

x - 8 y = 21 | (equation 2)

Subtract 1/3 × (equation 1) from equation 2:

{3 x - 8 y = 15 | (equation 1)

0 x - (16 y)/3 = 16 | (equation 2)

Multiply equation 2 by 3/16:

{3 x - 8 y = 15 | (equation 1)

0 x - y = 3 | (equation 2)

Multiply equation 2 by -1:

{3 x - 8 y = 15 | (equation 1)

0 x+y = -3 | (equation 2)

Add 8 × (equation 2) to equation 1:

{3 x+0 y = -9 | (equation 1)

0 x+y = -3 | (equation 2)

Divide equation 1 by 3:

{x+0 y = -3 | (equation 1)

0 x+y = -3 | (equation 2)

Collect results:

Answer:  {x = -3 , y = -3

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It takes 63 pounds of seed to completely plant a 7 acre field. How many acres can be planted per pound of seed?
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0.11 acres can be planted per pound of seed

<em><u>Solution:</u></em>

Given that it takes 63 pounds of seed to completely plant a 7 acre field

To find: acres can be planted per pound of seed

Let "x" be the acres which can be planted per pound of seed

Therefore, from given question,

63 pounds of seed = 7 acre field

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Multiply the numerator of the left-hand fraction by the denominator of the right-hand fraction

Multiply the numerator of the right-hand fraction by the denominator of the left-hand fraction

Set the two products equal to each other

Solve for the variable

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Answer:

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Step-by-step explanation:

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