Question

-4x+y=6
-5x+y=21
Solving system of equations by substitutions?

Answer 1

Solve for one variable and plug that into the other equation; substitute an x or y value to make one equation.

Answer 2

-4x +y = 6
y = 6+4x

-5x +y = 21
-5x + 6 +4x = 21
-x = 21-6
-x = 15
x = -15

y = 6+4x
y = 6 + 4*(-15)
y = 6 - 60
y = - 54

Answer 3

yes.

Answer 4

@adamaero that's what i try doing but didnt make sense and @sangya21 i dont think -54 is gonna plugin into the graph i have?

Answer 5

@originaal_elizabeeth the method I showed above is the method of substitution

As for graph, you can put x = 0,1, 2 and so on to find the value of y. and then plot that graph

Answer 6

y = y
6 + 4 x = 21 + 5 x
6 - 21 = 5x - 4x
x = -15
y = 6 + 4(-15) = 6 - 60 = - 54

check the original maybe you meant 2 and not 21 so that x = 4
with x = 4 y = 22

Answer 7

by the way, what @sangya21 did is correct using substitution method

Answer 8

this is the same thing im learning right now! ugh the struggle :/