What is 4x+8y=20,-4x+2y=-30 ?

The solution to 4x+8y=20,-4x+2y=-30 is x=7,y=-1

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4x+8y=20,-4x+2y=-30

4 x + 8 y = 20, - 4 x + 2 y = - 30

x = 7, y = - 1

Solution steps

[4 x + 8 y = 20 - 4 x + 2 y = - 30]

Isolate

x

for

4 x + 8 y = 20 : x = 5 - 2 y

Substitute

x = 5 - 2 y

[- 4 (5 - 2 y) + 2 y = - 30]

Simplify

[- 20 + 10 y = - 30]

Isolate

y

for

- 20 + 10 y = - 30 : y = - 1

For

x = 5 - 2 y

Substitute

y = - 1

x = 5 - 2 (- 1)

5 - 2 (- 1) = 7

x = 7

The solutions to the system of equations are:

x = 7, y = - 1

x + y = 4, x - y = 4

2 x - 5 y = 11, 3 x + 6 y = 3

5 x + 3 y = 6, 5 x + y = 4

\frac{x}{13} - \frac{y}{7} = 6, x - 10 y - 8 = 0

2 \cdot 3^{x} - 3 \cdot 2^{y} = 42, 3^{x + 1} - 2^{y + 1} = 73