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Nastasia [14]
2 years ago
9

Solve the simultaneous equations 3x + y = 25 2x – y = 10

Mathematics
1 answer:
Darina [25.2K]2 years ago
4 0

Answer:

x=7 and y=4

Step-by-step explanation:

I will use the elimination method:

Since the co-efficient of both y's are the same number but different signs we add the 2 equations to eliminate the y:

3x + y =25
+     +     +

2x - y = 10

Simplify:

5x=35

Divide both sides by 5:

5x÷5=35÷5

Simplify:

x=7

Substitute this into either equation 1 or 2 ( I chose 1):

3(7) + y = 25

21 + y = 25

Subtract 21 from both sides and simplify to get y:

21+y-21=25-21

y=4

Therefore x=7 and y=4

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4x + 3(4x + 7) = 4(7x + 3)​
Natasha2012 [34]

Answer: 1

Step-by-step explanation:4x + 3(4x + 7) = 4(7x + 3) + -3

Reorder the terms:

4x + 3(7 + 4x) = 4(7x + 3) + -3

4x + (7 * 3 + 4x * 3) = 4(7x + 3) + -3

4x + (21 + 12x) = 4(7x + 3) + -3

Reorder the terms:

21 + 4x + 12x = 4(7x + 3) + -3

Combine like terms: 4x + 12x = 16x

21 + 16x = 4(7x + 3) + -3

Reorder the terms:

21 + 16x = 4(3 + 7x) + -3

21 + 16x = (3 * 4 + 7x * 4) + -3

21 + 16x = (12 + 28x) + -3

Reorder the terms:

21 + 16x = 12 + -3 + 28x

Combine like terms: 12 + -3 = 9

21 + 16x = 9 + 28x

Solving

21 + 16x = 9 + 28x

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '-28x' to each side of the equation.

21 + 16x + -28x = 9 + 28x + -28x

Combine like terms: 16x + -28x = -12x

21 + -12x = 9 + 28x + -28x

Combine like terms: 28x + -28x = 0

21 + -12x = 9 + 0

21 + -12x = 9

Add '-21' to each side of the equation.

21 + -21 + -12x = 9 + -21

Combine like terms: 21 + -21 = 0

0 + -12x = 9 + -21

-12x = 9 + -21

Combine like terms: 9 + -21 = -12

-12x = -12

Divide each side by -12.

x = 1

Simplifying

x = 1

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3 years ago
A video has 42 thumbs down. What integer represents its score in points?
ioda

Answer:

Step-by-step explanation: it is negative 42 it is just the opposite cause the thumbs is down negative up positive

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2 years ago
Using Pythagoras, find the lengths of the sides labelled with letters.
vladimir1956 [14]

Answer:

Step-by-step explanation:

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2 years ago
By law, all businesses outside the Parkville city limits must fence their lots. How many inches of fence will be needed to fence
noname [10]
There is no picture down below....
8 0
3 years ago
Le
juin [17]
Total age of pupils
= 12.7 x 10
= 127 years

127 - 11 - 10 - 12 - 11 - 14 - 13 - 14 - 16 = 26 ( total age of the other 2 pupils added together )

however, since the ninth pupil is two years younger,

26-2=24
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thus, (a) 12 years old,
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