Question

Solve using the elimination method. If the system has no solution or an infinite number of solutions, state this.

10x – y = 12.5
3x + y = 7

Answer 1

do you add the two equations to cancel out the y

Answer 2

Yes, you do!

Answer 3

10x - y = 12.5
3x + y = 7
13x = 19.5
x = 1.5

10(1.5) - y = 12.5
15 - y = 12.5
-y = .83333
y = - .833333

Answer 4

good up to
15 - y = 12.5
or
15= 12.5+y
15-12.4=y

Answer 5

*15-12.5= 2.5

Answer 6

10(1.5) - -.833 = 12.5
15 + .8333 = 12.5
15.8333 = 12.5

3(1.5) + -.833 = 7
4.5 - .833 = 7
3.667 = 7
is this right

Answer 7

of course not. 15.8333 does not equal 12.5
see post above for your mistake

Answer 8

i am writing this down so might take a min
ok i am looking now

Answer 9

why did you rearrange the problem? it it to get y by itsself

Answer 10

habit. I don't like -y= stuff . It does not matter until you do < problems instead of =
if you like:
15 - y = 12.5
-y= 12.5-15
-y= -2.5
y= 2.5 (multiply both sides by -1)

Answer 11

all you do is substitute then right

Answer 12

yes (to check the answer) and it should work this time.

Answer 13

ty for your help