Question

1,Sovle using the substitution method. Show your work. If the system has no solution or an infinite number of solutions,state this.
-x - 3y = -20
5x + 3y =40

2 Sovle using the elimination method. Show your work. If the system has no solution or an infinite number of solutions, state this
-3x + 4y = 1
-6x + 6y = -3
and
-2x + 3y = -37.5
-4x + 0y = -24

Answer 1

form the 2nd equation: 3y = 40-5x
sub into the first:
-x - (40-5x) = -20
-x - 40 + 5x = -20
4x = 20
x = 5
sub into 3y = 40-5x
3y = 40-25
3y =15y=5
so x=5, y=5

2nd problem:
-3x + 4y = 1
-6x + 6y = -3
multiply the first by -2 to get
6x - 8y = -2
add the 2nd
-6x + 6y = -3 to get
-2y = -5
y = 5/2
sub into original first
-3x + 4(5/2) = 1
-3x = 1 - 10
x = 3

for the last did you notice if you divide the 2nd equation by -4 you get the value of x ?
I will let you finish it.