5x - 2y = -5
y - 5x = 3
2007-09-17 09:33:14 · 8 answers · asked by Jerry Z 1 in Science & Mathematics ➔ Mathematics
5x = y - 3
y - 3 - 2y = - 5
- y = - 2
y = 2
5x - 4 = - 5
5x = - 1
x = - 1 / 5
x = - 1 / 5 , y = 2
2007-09-18 23:59:15 · answer #1 · answered by Como 7 · 1⤊ 0⤋
first solve for y in the second equation.
y - 5x + 5x = 3 + 5x
y = 3 + 5x
Now you want to substitute (3 + 5x) in for y in the first equation.
5x - 2 (3 + 5x) = - 5
5x - 6 - 10x = -5
-5x - 6 = - 5
-5x - 6 + 6 = - 5 + 6
-5x = 1
x = 1/-5
x= -(1/5)
so it is negative one fifth.
And to get the y value you substitute (-1/5) in for x.
so it would look like
y - 5 (-1/5) = 3
y + 1 = 3
y = 2
I hope this helps, just remember solve the easiest one first then substitute the answer in.
Well good luck
2007-09-17 09:48:22 · answer #2 · answered by c_greiff 3 · 2⤊ 1⤋
To use substitution, you need to solve one of the equtions for either x or y, then "substitute" it into the other equation...
In this problem the y-5x=3 looks easy to solve for y, just add 5x to both sides....
Now you have y=5x+3... if both y's must be equal when we solve it... then the y in 5x-2y= -5 must also be equal to 5x+3... so replace it
5x - 2 (Y) = -3
5x - 2 (5x+3) = -3
now you have an equation with only one variable, x.
solve it and find the value of x...
Then plug it back into one of the original equations to find the value of y...
Good luck
2007-09-17 09:41:57 · answer #3 · answered by Pat B 3 · 0⤊ 2⤋
Pick an equation, pick a variable, and solve for that variable:
2nd eqn:
y - 5x = 3
Solve for y:
y = 3 + 5x
Now substitute y in to first eqn and solve for x:
5x - 2(3 + 5x) = -5
5x - 6 - 10x = -5
-5x = 1
x = (-1/5)
Now put back in to 2nd eqn and solve for x:
y - 5(-1/5) = 3
y + 1 = 3
y = 2.
2007-09-17 09:41:03 · answer #4 · answered by miggitymaggz 5 · 1⤊ 1⤋
5x - 2y = -5 (1)
y - 5x = 3 (2)
subst (2) into (1)
5x - 2(5x + 3) = -5
5x - 10x - 6 + 5 = 0, -5x = 1, x = -1/5
y = 2
2007-09-17 09:44:29 · answer #5 · answered by tj is cool 5 · 1⤊ 2⤋
y = 3 +5x
5x -2(3+5x) = 3
5x - 6 - 10x = 3
-5x = 9
x = 9/5
y = 3 + 5*9/5
y = 3 +9
y = 12
2007-09-17 09:41:24 · answer #6 · answered by Steve B 6 · 0⤊ 4⤋
substitute y = 5x + 3 into the first equation.
So you have 5x -2 (5x + 3) = -5
or 5x - 10x - 6 = -5
or -5x - 6 = -5
or -5x = 1
or x = -1/5
2007-09-17 09:36:42 · answer #7 · answered by ccw 4 · 0⤊ 2⤋
ok so we were just learning this in my grade 10 math class.
so 5x-2y=-5 is equation one, and y-5x=3 is equation 2
switch around the order of equation 2 : y=-5x+3
so now in equation 1, where it says y. sub in -5x+3 (thats what y equals)
so the new equation is 5x-2(-5x+3)=-5
so now solve
5x-10x-6=-5
so now simplify
5x-10x = -5x
6 - 5 = 1
so then its
5x = 1
then you haveto divide 5x by 5 to get x by itself.
so the answer is 1/5
2007-09-17 09:42:43 · answer #8 · answered by ain't nobody but me.. 2 · 0⤊ 3⤋