i need help solving a system of equations?

Question

1/5x-y=7
x-5y=35


they ask me to solve by substitution

even by addition i dont understand ...


dont you usually need x= or y= on one side of the equation?

Answer 1

Well yes, and that is the first step that you must do.

Pick the first one (let us say) and find out what y is:

1/5 x - y = 7

1/5 x - 7 = y

Once you have a 'value' for y (= 1/5 x - 7), use that instead of y in the second equation (you are substituting the value of y):

x - 5( 1/5 x - 7) = 35

You will be left with 35 = 35 (no sign of x) which normally indicates that something is strange. In this case (because you end up with something that is true), I suspect that both equations represent the same line. Let's check:

write each one in the standard format of y = mx + c

(1) y = 1/5 x - 7 (we had already found that above).

(2) x - 5y = 35

-5y = -x + 35
y = -x/-5 + 35/-5
y = 1/5 x - 7

So, at every point, one line is exactly on top of the other line. Therefore, any value of x will satisfy the equation (the two lines touch everywhere).

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(I made a mistake with the sign the first time around)

Answer 2

first you need to get the variable on one side

x-5y=35

so you get the x by itself
x=35-5y

now that you know what x is, substitue it into the other problem

1/5(35-5y)-y=7

now you have to distribute to get the parenthesis out

1/5 times 35=7
1/5-5y= negative 4.8

now your problem is 7 + 4.8y-y=7

next add like terms

7+3.8y=7

subtract 7 from both sides

3.8y=0

you take 0 divided by 3.8 and get 0

now you know what y is, so you put that into the problem to get x

x-0=35

x=35
y=0
hope it helps!

Answer 3

5x + 2y = 15 -5x - 2y = -5 _____________ 0 = 10 you remedy employing combining words, you upload the two equations. 0=10 ability this technique of equation has no answer in any respect, because of the fact the slopes of the two strains are the comparable, in different words are parallel strains, so there is not any longer factor of interception

Answer 4

yes you do.
you would take either equation and make it into a x= or y=
by getting all terms to one side except the x or y.
then substitute that answer into the x or y of the other equation.