Need to quickly do this maths and stuck HELP!?

Question

Solve these simultaneous equations

4x+2y=36
5x+4y=54

x=
y=

9x+7y=55
2x+28y=118

x=
y=


x+9y=95
2x+6y=70

x=
y=


5x+10y=50
6x+6y=36

x=
y=




ne1 help? i cnt do this nd has to be dun soon?

thanks :) i think i get it now. :)

Answer 1

I will do the first, by elimination.

a) 4x+2y=36, mult a by 2
b) 5x+4y=54

a) 8x+4y=72
b) 5x+4y=54, subtract
---------------
3x = 18 or
x = 6.

subs in either

b) 5x+4y=54 becomes
5*6+4y=54 or
30 + 4y = 54, gather
4y = 24 or
y = 6.

Repeat, do the rest.

Answer 2

From your first equation 4x+2y=36 you get a value of x=(36-2y)/4 or x=(18-y)/2

Substitute this in you second equation gives
5((18-y)/2 + 4y = 54
Multiply that out and you get

90/2-5y/2 +4y =54



-5y/2+4y=54-45=9

multiply through by 2 gives

-5y+8y=18 or 3y=18 y=6 therefore x=(18-6)/2 =6

That's going to work for all your homework questions. So you can do the rest.

Answer 3

4x+2y=36
5x+4y=54

x=
y=

9x+7y=55
2x+28y=118

x=
y=


x+9y=95
2x+6y=70

x=5
y=10


5x+10y=50
6x+6y=36

x=2
y=4

In a rush can only do these the last two

Answer 4

1 Multiply the first equation by 2 and subtract the second
You get 3x = 18, so x=6, y=6

2 Multiply the first equation by 4 and subtract the second
You get 34x = 102, so x=3, y=4

3 Multiply the first equation by 2 and subtract the second
You get 12y = 120, so y=10, x=5

4 Multiply the first equation by 3/5 and subtract the second
You get -3x = -6, so x=2, y=4

Answer 5

I've the first one:

4x+2y=36
5x+4y=54

8x+4y=72
5x+4y=54
subtract them so
3x=18
x=6
sub x into 5x+4y=54
5x6+4y=54
30+4y=54
y=6

Answer 6

4x+2y=36 <-- Eq 1
5x+4y=54 <-- Eq 2
-8x -4y= -72 <-- Eq 3 = -2 * Eq 1
-3x = -18 <-- Eq2 + Eq 3
x = 6
4(6) +2y =36 <-- Plug x =6 into Eq 1
2y = 12 --> y = 6

The rest are done in similar fashion

Answer 7

what pbb 1001 said!
you need to make it so that they have the same amount of either y's or x's (by multiplying)
and then take one off the other
and then you should be able to do it from there!