I need a step by step explanation on how you solved the equation. Use substitution to solve the system of equations.
1. x = -2y - 1
4x - 4y = 20

x=3 and y=−2

Step-by-step explanation:

x=−2y−1;4x−4y=20

Step: Solve x=−2y−1 for x:

Step: Substitute−2y−1 for x in 4x−4y=20:

4x−4y=20

4(−2y−1)−4y=20

−12y−4=20(Simplify both sides of the equation)

−12y−4+4=20+4(Add 4 to both sides)

−12y=24

−12y

−12

=

24

−12

(Divide both sides by -12)

y=−2

Step: Substitute−2 for y x=−2y−1:

x=−2y−1

x=(−2)(−2)−1

x=3(Simplify both sides of the equation)

or

step-by-step explanation:

we need to solve for 'x' the following equation:  

we have that:

⇒

⇒ ⇒

factorizing, we get that:

  ⇒

then, the solutions are: or

nothing extraneous has been found!