Question

x+y=4
2x-y=5
What is the solution to this system?

Answer 1

use elimination method

Answer 2

add down using elimination method

Answer 3

add
solve for x
then solve for y
I think it will be easier

Answer 4

multiply both side of x+y=4 by 5
and
multiply both side of 2x-y=5 by 4

Answer 5

I think adding two equation will give you in x terms only... no ned to go in a roundabout way

Answer 6

Thank you SO MUCH! all of you @gerryliyana @Rosh007 @Mr.Me
I appreciate 100% :p

Answer 7

welcome :)

Answer 8

welcome..so u got it... O glad..

Answer 9

Is the answer suppose to be a decimal tho??

Answer 10

because i got -0.3333333333.. etc.

Answer 11

what did u get it??

Answer 12

show in -1/3

Answer 13

by using the elimination method ...
Oh okay @gerryliyana
then plug that in to x in x+y=4 ?

Answer 14

yes...
first you nd to eliminate one variable...
sinc there are two equations and two unknowns.. it would is possible...
but you won't get -0.3333.. in this case

Answer 15

yes

Answer 16

NO!!! you have two use the equations which are available to you

Answer 17

What would it be @Rosh007 because thats what i got, am i doing it wrong then??

Answer 18

ur right @JessNicole

Answer 19

Try using substitution and see if you got the same as me. (:

Answer 20

@jazy you made a mistake here
Solve for x in the first equation.
x + y = 4
Subtract y.
x = 4 - y

Substitute the value of x into the second equation. Solve for y.
2(4 - y) = 5 ----- mistake

Answer 21

be careful @jazy
2(4 - y) = 5 ????
the right is
2(4 - y) - y= 5

Answer 22

Oh okay now I see.

Answer 23

@jazy THANK YOU!!! it makes sence but @Rosh007 how is it a mistake?

Answer 24

be careful @jazy
the mistake at
2(4 - y) = 5 ????

the right is
2(4 - y) - y= 5

Answer 25

@JessNicole please look gerryliyana's reply

Answer 26

Ohh okayy, i see now soo, it'd be Distribute 8-y=5?? @Rosh007 and @jazy ??

Answer 27

jazzy missed one y there

Answer 28

@gerryliyana Thank youuuu!!:) for catching that mistake, i fixed it on my paper!

Answer 29

no

Answer 30

I prefer substitution.
x + y = 4
2x - y = 5

Solve for x in the first equation.
x + y = 4
Subtract y.
x = 4 - y

Substitute the value of x into the second equation. Solve for y.
2(4 - y) - y = 5
Distribute.
8 - 2y - y= 5
Subtract 8.
-2y - y = -3
-3y = -3
Divide both sides by -3.
y = 1

Now plug in the value of y(1) into any equation to solve for x.
x + y = 4
x + 1 = 4
Subtract 1
x = 3

----------------------------------

So
x = 3
and
y = 1

Answer 31

@gerryliyana What would it be then?

Answer 32

2(4 - y) - y= 5
8 - 3y = 5

Answer 33

2(4 - y) - y= 5
8 - 3y = 5

Answer 34

Thank you catching that mistake! (:

Answer 35

It should be right now!

Answer 36

yes you got it jazzy.. but a very simpl method is there

Answer 37

@JessNicole
2(4 - y) - y= 5
8 - 3y = 5

Answer 38

@jazy @Rosh007 @gerryliyana THANK YOUUUUUUUUU!! SO MUCH EVERYONE!!:D .. I'd give all of you guys each a medal if i could!!

Answer 39

sice answer is already wrote here( which I don't like to do write directly) it is for you to know that there is a simple method than this

Answer 40

@jazy you are welcome

Answer 41

@JessNicole ur welcome..., happy to help u :)

Answer 42

@Rosh007 There's an easier way ? cause you can teach it to me ..this stuff is hard for me, i'm always confused.

Answer 43

actually it is derivd from the method mentioned here.. It is actually a special case of this method..
it is applicabl here since
in one equation +y and in other equation -y is there
actually the problem is simple
x+y=4
2x-y=5



so when we add both equation (LHS with LHS and RHS with RHS)
you get
3x =9

which can be simplified quickly and reach the answer fast