i dont get it.................. substitution method?

Question

substitution method
y=2x-5
4x-y=7

thank u for all of your answers. there are all good, so i donot know who to chose for the best answer.
i will make a careful decision and you will see who i vote. keepp in mind that i think that all of your answers are good. thank you! :)

Answer 1

see it's easy
all u have to do is pick one of ur two equations , u can pick anyone which looks simplar to you,and move variables in sucha way that all x variabl are on one side and y on the other.
will pick the first equation
y=2x-5(it is already simplified as y is on one side of equality and the rest if the term is on the other side)
now u have the value of y in terms of x
put this value in the other equation in places of y
you will get
4x-(2x-5)=7
or 2x+5=7
or2x=2
or x=1
now u have the value of x
to find the value of y substitute all x by 1 in either of ur equations
i m substituting in eq1
y=2(1)-5
y= -3

hence ur sol is
x=1
y= -3

Answer 2

It is not very complicated.
You know that y is equal to 2x-5. Since y is the same as 2x-5 five you can replace y with 2x-5 in the second equation so that you only have one variable you need to solve for. So, the second equation becomes 4x-(2x-5)=7. Then you just solve for x. X ends up being 1. Then, you can subsitute 1 for x in the first equation to solve for y. y=2x-5 becomes y=2(1)-5. This means that y is -3.

x=1 and y= -3

Answer 3

easy part in math... you have 2 eq. Take the top eq. as your main eq. Then the 2nd eq, rearrange it to put y as a head of the equation. So that 4x-y=7 is rearranged and become 4x-7=y.
Substitute 4x-7 to y in y=2x-5. So that you will get 4x-7=2x-5. Again rearrage to get x value. 2x=2. Then x=1.Substitute x=1 into any two root equation. Eg y=2x-5. Then you will get y=2-5, y=-3. So the answer is x=1, y=-3. Recheck again. My answer might be wrong!!

Answer 4

First you know that y is the same as 2x-5. So if that is true, then 4x-y is the same as 4x-(2x-5). Since there is now one variable for the second equation, you can solve for x.

Now we know that x is the same as 1. So if x is 1 that means 2x-5 is the same as 2(1)-5. And you have one variable for the first equation.

Finally, you know that y is the same as -3.

This is all assuming that the two equations are co-dependent. If they are independent equations then you can not use substitution.

Answer 5

y=2x-5 put the first equation into the second and solve for x.
4x-y=7

4x-(2x-5)=7
4x-2x+5=7 subtract 2x from 4x and subtract 5 from both sides.
2x= 2 divide both sides by 2
x=1 now you can solve for y.

y=2x-5 put 1 in for x and solve.
y=2(1)-5
7=2-5
y=-3

now you can check to see if your right.
put x=1, y=-3 back into original equation
4x-y=7

4(1)-(-3)=7
4 + 3 = 7 True
This is the substitution method
I hope this helps.

Answer 6

y=2x-5
4x-y=7

Basically substitute whatever one of your variables is into the other equation:

4x -(2x - 5) = 7
4x -2x + 5 = 7
2x = 2
x = 1

Answer 7

do as the first girl has said. I seems simple for you to understand. Later when you get the hang of it go through the other answers. They are completely right and will help you solve a little complicated ones later . good luck.

Answer 8

You are given the "y" value so plug "y" into the other equation.

4x-(2x-5)=7
4x-2x+5=7
2x+5=7
2x=2
x=1

now plug you "x" value into the "y"-equals equation.

y=2(1)-5
y=2-5
y=-3

so your answer is (1,-3)

Answer 9

3a+b=6 and 9a+2b=1 is 3a=6-b and 9a=1-2b or a=(6-b/3) and a=(1-2b/9) 9(6-b/3) =1-2b 9(6-b)=3(1-2b) 9(6-b)=3-6b 54-9b=3-6b 51=3b finally b=17 Likewise 3a+17=6 which is 3a= -11 or a=11/3

Answer 10

i will only explain it, you can use the answers above to get the answer

we have this : ax+by = c and a_1x +b_1y = c_1 (_here is subscript)
we will calculate one root by the other for example x = (c-by)/a or
y = (c-ax)/b then we will put it into the second equation to find out the root that we use to calculate , after finding its value, we will put that value into the first equation to find out the second root

ax + by = c and a_1x+b_1y=c_1
=> x = (c-by)/x and a_1x + b_1y = c_1 { calculate x using y}
=> x = (c-by)/x and a_1(c-by)/y + b_1y =c1 { put the value into the second equation}

good luck