#1

So my little sister came from summer school today and quite frankly I feel like I should be going back also. I can't solve this.

Solve the system of equation using substitution.

y+3x=5

-2x+4y=-1

I've spent an hour and I can't get this. Someone help.

Solve the system of equation using substitution.

y+3x=5

-2x+4y=-1

I've spent an hour and I can't get this. Someone help.

#2

idk, i completely forgot how to do algebra. and i was in algebra 2 last semester

#3

y+3x=5

-2x+4y=-1

y= 5-3x

-2x+4*(5-3x)=-1

-2x + 20 - 12x = -1

-14x = -21

x=21/14 = 3/2

y= 5-3*3/2 = 10/2 - 9/2 = 1/2

30 seconds

-2x+4y=-1

y= 5-3x

-2x+4*(5-3x)=-1

-2x + 20 - 12x = -1

-14x = -21

x=21/14 = 3/2

y= 5-3*3/2 = 10/2 - 9/2 = 1/2

30 seconds

#4

Simultaneous Equations.

Not that hard.

Not that hard.

#5

y=5-3x

-2x+4(5-3x)=-1

Solve for x.

-2x+4(5-3x)=-1

Solve for x.

#6

Multiply the top one by -4, or else multiply top by 2, bottom by 3.

#7

x = 2

y = -1

I think that's it but don't take my word for it. I'm probably wrong anyways not that good at it.

y = -1

I think that's it but don't take my word for it. I'm probably wrong anyways not that good at it.

#8

Beats me.

#9

oh you guys are just sad

#10

Or just use simultaneous equations

#11

simultaneous equations. not hard, its Year 9 stuff

#12

oh you guys are just sad

I did it right seljer!

#13

y+3x=5

-2x+4y=-1

y= 5-3x

-2x+4*(5-3x)=-1

-2x + 20 - 12x = -1

-14x = -21

x=21/14 = 3/2

y= 5-3*3/2 = 10/2 - 9/2 = 1/2

30 seconds

This

#14

elimination or substitution

#15

ahhhhh im in year nine and dont understand it?????

#16

You have to make one equation have one variable opposite the same variable on the other equation then add the equations together, solve for the one variable, then plug it into one of the original equations and solve for the other variable.

#17

ahhhhh im in year nine and dont understand it?????

You will be repeating year 9 then.

#18

Multiply the top one by -4, or else multiply top by 2, bottom by 3.

thats not solving by substitution

#19

dude,, its f*kin summer,, lay off the math equations, maye then u wont feel so retarted

#20

Wow, Yep moron award of the day for me.

#21

thats not solving by substitution

Oh, I missed that part. Well substitution is even easier, so that makes it nicer for the TS.

#22

simultaneous equations. not hard, its Year 9 stuff

I learnt it in year 8.

#23

lol thats very basic maths you know ^^

#24

ahhhhh im in year nine and dont understand it?????

Thats cos ure thick :|

there are two ways to do it but i've forgotten the second way.

#25

...or use augmented matrix, simplify into reduced echelon form.

Row Operation 1:

3 1 5

-2 4 -1

multiply the 1st row by 1/3

1 1/3 5/3

-2 4 -1

Row Operation 2:

1 1/3 5/3

-2 4 -1

add 2 times the 1st row to the 2nd row

1 1/3 5/3

0 14/3 7/3

Row Operation 3:

1 1/3 5/3

0 14/3 7/3

multiply the 2nd row by 3/14

1 1/3 5/3

0 1 1/2

Row Operation 4:

1 1/3 5/3

0 1 1/2

add -1/3 times the 2nd row to the 1st row

1 0 3/2

0 1 1/2

first column represents x = 3/2

second column represents y = 1/2

just felt like being a nerd heheh.

Row Operation 1:

3 1 5

-2 4 -1

multiply the 1st row by 1/3

1 1/3 5/3

-2 4 -1

Row Operation 2:

1 1/3 5/3

-2 4 -1

add 2 times the 1st row to the 2nd row

1 1/3 5/3

0 14/3 7/3

Row Operation 3:

1 1/3 5/3

0 14/3 7/3

multiply the 2nd row by 3/14

1 1/3 5/3

0 1 1/2

Row Operation 4:

1 1/3 5/3

0 1 1/2

add -1/3 times the 2nd row to the 1st row

1 0 3/2

0 1 1/2

first column represents x = 3/2

second column represents y = 1/2

just felt like being a nerd heheh.

#26

^^or be lazy and throw it into matlab (which probably isn't worth it for a system with 2 variables)