how do you solve this problem 3x-y=4 and 5x+7y=5
solve the system by subsitution method
Using the first equation, find y in terms of x.
3x - y = 4
-y = -3x + 4
y = 3x - 4
Now that we have something that represents the
value of y, we can substitute that into the second equation.
5x + 7y = 5
5x + 7(3x - 4) = 5
5x + 21x - 28 = 5
26x = 5 + 28
26x = 33
x = 33/26
We can substitute that into the first equation
and solve for y.
3x - y = 4
3(33/26) - y = 4
99/26 - y = 4
-y = 4 - 99/26 4 is (4 * 26)/26 = 104/26
-y = 104/26 - 99/26
-y = 5/26
y = -5/26
Are those values correct? Let's put them into
equation two and find out.
5x + 7y = 5
5(33/26) + 7(-5/26) = 5
165/26 - 35/26 = 5
130/26 = 5
5 = 5
The values are correct.
x = 33/26 and y = -5/26