Question

3x + 5y = 78
2x - y = 0

The point of intersection of the lines has an x-coordinate of _____.

78
6
-6

okay def lied , this question stumped me.
so far I did the elimination method and got
x+6y=78

Where do I take it from there?

Answer 1

well to get the answer for this... We have to multiply one equation by a factor so that when we add them we can get rid of one variable.

It wants the x-coordinate. So we need to eliminate the y's.
So we can multiply the whole second equation by 5.
And then we add both of the equations.

\(\sf 3x + 5y = 78\\
2x - y = 0\)

So that becomes
\(\sf 3x + 5y = 78\\
5\times (2x - y = 0)\)

And when we multiply by 5 to the second equation we get

\(\sf3x + 5y = 78\\
10x - 5y = 5\)

And now we can use elimination to solve it. To get rid of the y we need to add the equations

\(~~~\sf 3x + 5y = 78\\+\\
~~~10x - 5 = 5\\--------\)

Answer 2

thank you , sorry I'm cooking

Answer 3

but I cant add 5y to 5 they arent like terms

Answer 4

my bad. Typo it should be 5y.

Answer 5

at the end it should just be eliminated. :) :P

Answer 6

oh okay so , 13x = 83 ?

Answer 7

oh hold on lol missed a step

Answer 8

Nope, 13x= 83 is correct :)

Answer 9

oh, so I dont divide it out ? but I thought I was looking for "x"

Answer 10

One sec.. I think I made a mistake.

Answer 11

ok

Answer 12

my bad. *facepalm* I did \(5\times 0 =5\)

Answer 13

well to get the answer for this... We have to multiply one equation by a factor so that when we add them we can get rid of one variable.

It wants the x-coordinate. So we need to eliminate the y's.
So we can multiply the whole second equation by 5.
And then we add both of the equations.

\(\sf 3x + 5y = 78\\
2x - y = 0\)

So that becomes
\(\sf 3x + 5y = 78\\
5\times (2x - y = 0)\)

And when we multiply by 5 to the second equation we get

\(\sf3x + 5y = 78\\
10x - 5y = 0\)

And now we can use elimination to solve it. To get rid of the y we need to add the equations

\(~~~\sf 3x + 5y = 78\\+\\
~~~10x - 5 = 0\\--------\)

Answer 14

Just look at the ending and add them together.

We should get 13x=78
and divide 13 and get the value of x :)

Answer 15

oh okay

Answer 16

6 !

Answer 17

6 is correct :)

Answer 18

Yes I'm happy I'm actually getting some help most people just throw me the answer !

Answer 19

That is what I'm here for-- to explain you how to do it. :)

If you ever need any help, tag me and/or message me. If I can't help you, I'll find someone who can :)

Answer 20

Wheres my answer? D:<