SOLUTION: This chap is asking to solve the system of equation using subsititution method but I keep getting the wrong ans. 9. 2x+y=5 x+3y=0 the book ans is (3,-1) 11. 2x+y=3

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: This chap is asking to solve the system of equation using subsititution method but I keep getting the wrong ans. 9. 2x+y=5 x+3y=0 the book ans is (3,-1) 11. 2x+y=3       Log On


   

Question 62125This question is from textbook beginning algebra
: This chap is asking to solve the system of equation using subsititution method but I keep getting the wrong ans.
9. 2x+y=5
x+3y=0 the book ans is (3,-1)
11. 2x+y=3
2y=-4x+6 the book ans is (Many solutions)
13. x-y=3
3y=x the book ans is (9/2,3/2)
15. 2x+y=-4
x-2y=-7 the book ans is (-3,2)
17. 4x+y=5
x-3=0
I am having problem solving using the substitution method. PLEASE HELP ME! This question is from textbook beginning algebra

Found 2 solutions by checkley71, Earlsdon:
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
I'LL SOLVE THE FIRST ONE & LEAVE THE REST FOR YOU
2X+Y=5
X+3Y=0 SOLVING THIS EQUATION FOR X WE GET
X=-3Y NOW SUBSTITUTE (-3Y) FOR X IN THE FIRST EQUATION
2(-3Y)+Y=5
-6Y+Y=5
-5Y=5
Y=5/-5
Y=-1 SOLUTION NOW SUBSTITUTE (-1) SECOND EQUATION
X+3(-1)=0
X-3=0
X=3 SOLUTION
NOW SUBSTITUTE BOTH VALUES (-1 FOR Y & 3 FOR X) THIS IS THE PROOF
2+3*-1=5
6-1=5
5=5 &
3+3*-1=0
3-3=0
0=0

Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Solve by substitution:
(9)
2x%2By+=+5
x%2B3y+=+0 Rewrite this as: x+=+-3y and substitute for x in the 1st equation.
2%28-3y%29%2By+=+5 Solve for y.
-6y%2By+=+5
-5y+=+5
y+=+-1 To find x, use: x+=+-3y
x+=+-3%28-1%29
x+=+3
Solution is: (3, -1)
(11)
2x%2By+=+3 Rewrite as: y+=+-2x%2B3 and substitute for y in the 2nd equation.
2y+=+-4x%2B6
2%28-2x%2B3%29+=+-4x%2B6 Simplify and solve for y.
-4x%2B6+=+-4x%2B6 Add 4x to both sides.
6+=+6 The two equations represent the same line so there are an infinite number of solutions.
(13)
x-y+=+3
3y+=+x Substitute this for x in the 1st equation and solve for y.
3y-y+=+3
2y+=+3
y+=+3%2F2
x+=+3y Substitute y+=+3%2F2
x+=+3%283%2F2%29
x+=+9%2F2
Solution is: (9/2, 3/2)
(15)
2x%2By+=+-4
x-2y+=+-7 Rewrite this as: x+=+2y-7 and substitute for x in the 1st equation.
2%282y-7%29%2By+=+-4 Simplify and solve for y.
4y-14%2By+=+-4
5y-14+=+-4
5y+=+10
y+=+2
x+=+2y-7 Substitute y+=+2 and solve for x.
x+=+2%282%29-7
x+=+-3
The solution is: (-3, 2)
(17)
4x%2By+=+5
x-3+=+0 Rewrite this as: x+=+3 and substitute for x in the 1st equation and solve for y.
4%283%29%2By+=+5
12%2By+=+5
y+=+-7
The solution is: (3, -7)