How do you solve the following system?: 4x + 5y = 2 , 17 x + 2y = 6

2 Answers
Apr 5, 2017

x=26/77
y=10/77

Explanation:

There are a couple of ways we can solve this. I'm going to use the elimination method
4x+5y=2
17x+2y=6

I need to make two of the variables equal, so I'm going to multiply the second equation by 2.5. That will change 2y into 5y.

4x+5y=2
2.5(17x+2y=6) or 42.5x+5y=15

Now we subtract the two equations:
4x+5y=2
-
42.5+5y=15
color(black)(------)
-38.5x+0y=-13

If we simplify our equation, we find that x=(-13)/-38.5 or x=26/77

Now we just solve for y. We can use either of the two equations. I like the first one (it has nicer numbers than 17).

4(color(purple)(x))+5y=2
4(color(purple)(26/77))+5y=2
cancel(104/77)+5y=2
cancel(-104/77)color(white)(+5y)-104/77

Now we have
5y=50/77
or
y=10/77.

To double check our work, we need to plug our values into one (or both) of the equations.
4(26/77)+5(10/77) should equal 2
104/77+50/77
2=2, so we were right!
Just to be safe, let's look at the other equation.

17(26/77)+2(10/77) should equal 6
442/77+20/77
6=6
Good job, we got it right! Nice work

Apr 5, 2017

Using the process of elimination, we find that x=0.338 and y=0.130. (See explanation)

Explanation:

We can solve this system of equations using the elimination method. First, we can set up the system in such a way that the y terms cancel out. To do this, we need both the y terms in each equation to have the same coefficient (one negative and one positive):

2(4x+5y=2)
-5(17x+2y=6)

So we get:
8x+10y=4
-85x-10y=-30

Adding these two equations together gives us:
-77x=-26

x=26/77=0.338

Plug this value of x back into one of the given equations:
4(0.338)+5y=2

y=(2-4(0.338))/5=0.130

So, x=0.338 and y=0.130