How do you solve 6x + 2y = -26x+2y=2 and 4x + y = 14x+y=1 using substitution?

1 Answer
Jun 20, 2017

See a solution process below:

Explanation:

Step 1) Solve the second equation for yy:

4x + y = 14x+y=1

-color(red)(4x) + 4x + y = -color(red)(4x) + 14x+4x+y=4x+1

0 + y = -4x + 10+y=4x+1

y = -4x + 1y=4x+1

Step 2) Substitute (-4x + 1)(4x+1) for yy in the first equation and solve for xx:

6x + 2y = -26x+2y=2 becomes:

6x + 2(-4x + 1) = -26x+2(4x+1)=2

6x + (2 * -4x) + (2 * 1) = -26x+(24x)+(21)=2

6x + (-8x) + 2 = -26x+(8x)+2=2

6x - 8x + 2 = -26x8x+2=2

(6 - 8)x + 2 = -2(68)x+2=2

-2x + 2 = -22x+2=2

-2x + 2 - color(red)(2) = -2 - color(red)(2)2x+22=22

-2x + 0 = -42x+0=4

-2x = -42x=4

(-2x)/color(red)(-2) = (-4)/color(red)(-2)2x2=42

(color(red)(cancel(color(black)(-2)))x)/cancel(color(red)(-2)) = 2

x = 2

Step 3) Substitute 2 for x in the solution to the second equation at the end of Step 1 and calculate y:

y = -4x + 1 becomes:

y = (-4 * 2) + 1

y = -8 + 1

y = -7

The solution is: x = 2 and y = -7 or (2, -7)