Question

How do I solve this question 4x - 5y =17 & 3x + 4y = 5 using elimination?

Answer 1

The usual ides is rather like a common denominator. We really need a common multiple of something. You can pick the coefficients fo x or those of y.

x- coefficients 4 and 3. What is the least common multiple of 4 and 3?

Answer 2

12?

Answer 3

Perfect. The task is to alter the two equations so that the solution is unaltered but something matches up conveniently.

Original
4x - 5y =17 <== Multiply this by 3
3x + 4y = 5 <== Multiply this by 4

Altered

12x - 15y =51
12x + 16y = 20

See how that works? We now have the same coefficient for x in both equations.

Answer 4

Oooh ok I see now ok hold on

Answer 5

I got a decimal idk y I think I did something wrong

Answer 6

Please show your intermediate results. What's wrong with fractions or decimals? What did you get when you subtracted the two altered equations?

Answer 7

Y=31

Answer 8

That's no good. This is why I like to do it a little differently. Subtraction, it turns out, is too complicated. Multiply one of the equations by -1 and then ADD. It is much harder to make errors.

This and subtract? No
12x - 15y = 51
12x + 16y = 20

This and ADD?o
12x - 15y = 51
-12x - 16y = -20

Okay, now what do you get when you add the slightly additionally altered equations?

Answer 9

Is the result gonna be 3, 1?

Answer 10

-1 sorry

Answer 11

Please show your work. Don't leave me guessing what you did. It is so much more difficult to have a helpful conversation. What did you get after ADDING the equations?

Answer 12

Ok

Answer 13

Did the addition thing work better for you AND make sense?

Answer 14

no and theres something I did wrong

Answer 15

Hold on tho

Answer 16

I got 31y = 30

Answer 17

You keep dropping that negative sign. Poor thing. Eventually, you will hurt its feelings. :-)

Answer 18

Thanx for helping