how do I solve this in steps
2x+3y=18
5x-y=11

Solve the bottom equation for y and sub into the top one. Then, the top one will be entirely in terms of x. Solve away.

2x+3y=18
5x-y=11

Multiply the second equation by 3.
Eliminate the ys.
Add up the xs and equivalents
Then take it from there.

Quote:

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Originally Posted by Blahhh

how do i solve this in steps
2x+3y=18
5x-y=11

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Basics of solving the equations is that you need to make any element same in both the equations.

Like,
2x+3y=18 ------> equation 1
and 5x-y=11 -----> equation 2
now you have to see that how can you make one element equal in both the equations.
either multiply eq 1 by 5 and eq 2 by 2
then the equation will become,
10x+15y=90 ------> equation 3
and 10x-2y=22 -----> equation 4
So we got 10x as common in both the equations
But this was a little hectic because we have to do a lot of multiplication, we are humans and we are supposed to make things easier.
So, multiply equation 2 by 3, that's it
then the equation will become,
2x+3y=18 ------> equation 3
15x-3y=33------> equation 4
So we got 3y as common.
Now, add eq 3 to eq 4,
where +3y will cancel -3y
we'll get,
17x=51 => x=51/17 => x=3
Put the value of x in either eq1 or eq 2 and get value of y