Math

Question Solve the system of linear equations to find the common solution.
x+y=20x+y=20 and y=2x1y=2x-1 y=2xy=2x and y=6x+4y=-6x+4

Studdy Solution

STEP 1

Assumptions
1. We are given two systems of linear equations.
2. Each system has two equations with two variables, xx and yy.
3. We need to find the common solution for each system, which means finding the values of xx and yy that satisfy both equations in the system.

STEP 2

Solve the first system of equations:
x+y=20y=2x1 \begin{array}{l} x + y = 20 \\ y = 2x - 1 \end{array}

STEP 3

Substitute the expression for yy from the second equation into the first equation.
x+(2x1)=20 x + (2x - 1) = 20

STEP 4

Combine like terms in the equation.
3x1=20 3x - 1 = 20

STEP 5

Add 1 to both sides of the equation to isolate the term with xx.
3x=21 3x = 21

STEP 6

Divide both sides by 3 to solve for xx.
x=7 x = 7

STEP 7

Now that we have the value of xx, we can substitute it back into the second equation to solve for yy.
y=2(7)1 y = 2(7) - 1

STEP 8

Calculate the value of yy.
y=141 y = 14 - 1
y=13 y = 13

STEP 9

The common solution for the first system of equations is x=7x = 7 and y=13y = 13.

STEP 10

Now, solve the second system of equations:
y=2xy=6x+4 \begin{array}{l} y = 2x \\ y = -6x + 4 \end{array}

STEP 11

Since both equations equal yy, we can set them equal to each other to find xx.
2x=6x+4 2x = -6x + 4

STEP 12

Add 6x6x to both sides of the equation to get all xx terms on one side.
8x=4 8x = 4

STEP 13

Divide both sides by 8 to solve for xx.
x=48 x = \frac{4}{8}

STEP 14

Simplify the fraction to find the value of xx.
x=12 x = \frac{1}{2}

STEP 15

Now that we have the value of xx, we can substitute it back into either of the original equations to solve for yy. We'll use the first equation.
y=2(12) y = 2 \left(\frac{1}{2}\right)

STEP 16

Calculate the value of yy.
y=1 y = 1

STEP 17

The common solution for the second system of equations is x=12x = \frac{1}{2} and y=1y = 1.
The solutions to the systems of equations are:
For system 7: x=7,y=13 x = 7, y = 13
For system 8: x=12,y=1 x = \frac{1}{2}, y = 1

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