Question

Solve by substitution.
(x - 4y = 20
2x + 5y = 1
([? ], [ ])

Answer 1

x, y =8 -3

Explanation:

System of Linear Equations entered :

[1] x - 4y = 20

[2] 2x + 5y = 1

Graphic Representation of the Equations :

-4y + x = 20 5y + 2x = 1

Solve by Substitution :

// Solve equation [1] for the variable x

[1] x = 4y + 20

// Plug this in for variable x in equation [2]

[2] 2•(4y+20) + 5y = 1

[2] 13y = -39

// Solve equation [2] for the variable y

[2] 13y = - 39

[2] y = - 3

// By now we know this much :

x = 4y+20

y = -3

// Use the y value to solve for x

x = 4(-3)+20 = 8

Solution :

{x,y} = {8,-3}