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3x + 3y = 11.25 \\ 4x + 2y = 10

solve for elimination and substitution, please helppp.


User Qbeuek
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2 Answers

4 votes
it would be x= 1.25, y=5/2
User Abdullah Aden
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1 vote

Answer:

x = 1.25

y = 2.5

(1.25, 2.5)

Explanation:

ELIMINATION

To use elimination, multiply or divide the entire equation until either the "x" or the "y" are the same in both equations.

3x + 3y = 11.25 ÷ 3 => x + y = 3.75

4x + 2y = 10 ÷ 2 => 2x + y = 5

"y" in both equations is equal to 1.

Subtract one equation from the other. This will get rid of the variable "y" because y - y = 0.

. 2x + y = 5 Subtract each term

- x + y = 3.75 Do 2x-x=x and y-y=0 and 5-3.75 = 1.25

. x = 1.25 Solved for "x"

Substitute x = 1.25 into any of the equations to find "y".

4x + 2y = 10

4(1.25) + 2y = 10 Multiply 4 and 1.25

5 + 2y = 10 Isolate "y" now

2y = 10 - 5 Subtract 5 from both sides

2y = 5 Divide both sides by 2

y = 5/2 Answer in fraction form

y = 2.5 Answer in decimal form

The point as an ordered pair is (1.25, 2.5). Or x = 1.25 and y = 2.5.

SUBSTITUTION

To use substitution, rearrange one of the equations so that it equals an isolated variable. I will rearrange 4x + 2y = 10 and isolate "y".

4x + 2y = 10

2y = 10 - 4x Subtract 4x from both sides

y = 5 - 2x Divide both sides by 2

Substitute y=5-2x into the other equation, replacing "y".

3x + 3y = 11.25

3x + 3(5-2x) = 11.25 Use the distributive property multiplying over brackets

3x + 15 - 6x = 11.25 Combine like terms (3x - 6x = -3x)

15 - 3x = 11.25 Isolate "x" variable now

-3x = 11.25 - 15 Subtract 15 from both sides

-3x = -3.75 Divide both sides by -3

x = 1.25 Answer

Substitute x = 1.25 in any of the equations.

y = 5 - 2x

y = 5 - 2(1.25) Multiply 2 and 1.25

y = 5 - 2.5 Subtract

y = 2.5 Answer

The point as an ordered pair is (1.25, 2.5). Or x = 1.25 and y = 2.5.

User Karim
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