Check out some similar questions!

mica121169 · Jul 23, 2008, 09:00 PM

I have tried to see both ways of eliminationa and substitution and I am having a hard time with this problem. I have the answer, I want to see how to GET the answer. I need to see work and steps please, and thank you. By the way, the answer is (4,2)
7x-2y=24
5x+4y=28

TmichelleO · Jul 23, 2008, 09:15 PM

are you sure you have the problem right? I got x but when you plug x in y does not equal 2

TmichelleO · Jul 23, 2008, 09:17 PM

actually I lied here you go!

multiply the first equation by 2 so it will be...
14x-4y=48
5x+4y=28
add it together
19x=76
4=x

plug in x to second equation

5(4)+4y=28
20+4y=28
4y=8
y=2

sorry I struggled for a minute I haven't had to do that in a few years!

Unknown008 · Jul 24, 2008, 02:40 AM

Both can be used, though elimination is shorter. Here we go for substitution, if you would like to spot your mistake (you said that you struggled to get the answer from both methods)

7x-2y=24
5x+4y=28

Make 'y' subject of formula in first equation.
$-2y=24-7x$

$y=\frac{24-7x}{-2}$

Substitute in the second equation:

$5x + 4(\frac{24-7x}{-2}) = 28$

$5x - 2 (24-7x) = 28$

$5x - 48 + 14 x = 28$

$19x - 48 =28$

$19x = 76$

$x = 4$

$y = \frac{24-7(4)}{-2}$

$y = \frac{-4}{-2}$

$y = 2$

Here!

bella06 · Feb 26, 2010, 07:50 AM

b=2-3a
5a-3b=14

Unknown008 · Feb 26, 2010, 10:41 AM

What did you try bella06?