Answer:
1. (-6,-11)
2.(-2,5)
Step-by-step explanation:
y=2x+1
2x-3y =21
Take the first equation and substitute into the second
2x-3(2x+1) =21
Distribute
2x -6x-3 = 21
Combine like terms
-4x -3 = 21
Add 3 to each side
-4x-3+3 =21+3
-4x = 24
Divide by -4
-4x/4 = 24/-4
x = -6
Then find y
y = 2x+1 = 2(-6) +1 =-12+1 = -11
Elimination for problem 2
2x+3y=11 4x-3y=-23
Add the two equations together to eliminate y
2x+3y=11
4x-3y=-23
-----------------
6x = -12
Divide by 6
6x/6 = -12/6
x = -2
Multiply the first equation by -2
-4x+-6y=-22
4x-3y=-23
-----------------
-9y = -45
Divide by -9
-9y/-9 = -45/-9
y = 5
