I need help with math. What are the values of x and y?

Question

y=2x+5
3x-y=4

3x+2y=71
y=4+2x

y=3x+8
x=y

x-7y=13
3x-5y=23

Answer 1

y=2x+5
3x-y=4

First, bring 2x over to the left side:
-2x + y = 5
3x - y = 4
...and the y's can cancel out. Add -2x and 3x, and 5 and 4 to get x=9. Plug in 9 for y=2x+5, or y=2(9) + 5 to get y=23.

---
3x+2y=71
y=4+2x

Again, move 2x to left side and get..
3x + 2y = 71
-2x + y = 4
...then I would multiply the entire second equation by -2 so that the +2y could cancel out the -2y. so...
3x + 2y = 71
4x - 2y = -8
...and 2y's cancel out. Add 3x and 4x, and 71 and -8 to get 7x = 63. Therefore x = 9. Plug in 9 in y=4+2x, which is y=4+2(9), and y= 22.

Hopefully this helped you a bit. The other two I'll leave for other people.

Answer 2

y=2x+5
3x-y=4 3x+2x+5=4 5x=-1 x= =1/5 y=4 3/5

3x+2y=71
y=4+2x 3x+2(4+2x)=71 3x+8+4x=71 7x=63 x=9 y=22

y=3x+8
x=y x=3x+8 -2x=8 x=-4 y+-4

x-7y=13 3x-21y=39 -16y=16 y=-1 x=6
3x-5y=23

Answer 3

I'm assuming that these are simultaneous equations. There are 2 ways to solve any pair of simultaneous equations. The first way is to solve 1 of the equations for 1 of the variables and then substitute that into the second equation.
Problem 1 is a perfect example, it is already solved for y,
y = 2x + 5 substitute that into the second equation for y and get 3x -2x -5 = 4. (NOTE the signs in front of 2x and 5. The equation says -Y so you have to put the negative in front of both). This reduces to x = 9. Substitute that back into the first equation and solve for y = 2*9+5 = 23.
Problem 2 , 3x +4x +8 =71 gives 7x = 63 or x = 9, so y= 22
Problem 3 , y = 3y + 8 gives -2y = 8, y = -4 and x =-4
For Problem 4, I'm going to use the second approach. In the second approach, you multiply one of the equations by a constant and then add the equations together. You select the constant to eliminate one of the variables. I'm going to eliminate X by using the constant -3 and multiplying the first equation by it:
-3x +21Y =-39
3x - 5Y = 23
---------------------
16Y = -16 so Y = -1
substitute back to get
x +7 = 13
so x = 6

Answer 4

PROBLEM 1:
y=2x+5
3x-y=4

Substitute y=2x + 5 into 2nd equation and solve for x:
3x - (2x+5) = 4
3x - 2x - 5 = 4
x - 5 = 4
x = 9

Substitute x=9 into 1st equation and solve for y:
y = 2x+5
y = 2(9)+ 5
y = 23

Check result:
Substitute x=9, y=23 into both equations:

y=2x+5
23 = 2(9) + 5
23 = 18 + 5
23 = 23 is true

3x-y=4
3(9) - 23 = 4
27 - 23 = 4
4 = 4 is true

So, x=9 y=23 are correct

Answer 5

3x-4 = 2x+5
x=9 y = 23

3x + 2(4+2x) = 71
3x + 8 + 4x = 71
7x = 63 x = 9

x = 3x + 8
2x = -8 x = -4 y = -4


x = 7y + 13
3(2y+13) - 5y = 23
6y + 39 - 5y = 23
y = -16 x = x = -19

Answer 6

Problem #1:

Eqn. 1: y = 2x + 5
Eqn. 2: 3x - y = 4

Substitute Eqn. 1 into Eqn. 2 to first sovle for x:

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

Now, solve your value of x into Eqn. 1 to solve for y:

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

Problem #2:

Eqn. 1: 3x + 2y = 71
Eqn. 2: y = 4 + 2x

Substitute Eqn. 2 into Eqn. 1 to first sovle for x:

3x + 2*(4 + 2x) = 71
3x + 8 + 4x = 71
7x = 63
x = 9

Subsitute x = 9 into Eqn. 2 to solve for y:

y = 4 + 2*(9)
y = 22

Problem #3:

Eqn. 1: y = 3x + 8
Eqn. 2: x = y

Substituting Eqn. 1 into Eqn. 2 yields:

x = 3x + 8
2x = -8
x = -4

Hence, from Eqn. 2:

y = -4

Problem #4:

Eqn. 1: x - 7y = 13
Eqn. 2: 3x - 5y = 23

Rearrange Eqn. 1 yields:

Eqn. 3: x = 7y + 13

Substituting Eqn. 3 into Eqn. 2 yields a solution for y:

3*(7y + 13) - 5y = 23
21y + 39 - 5y = 23
16y = -16
y = -1

Substituting y = -1 into Eqn. 1 yields:

x - 7(-1) = 13
x + 7 = 13
x = 6

Answer 7

in truth at the same time as x is next to the 4 and x = 2, you ought to cases 4 by 2 which = 8 so now the sum is 8 - 3 which = 5 for this reason Y = 5 it will be confusing the way they wright those sums, it would want to be more convenient to guage it as 4x - 3 =Y fairly than Y = 4x - 3

Answer 8

y=2x+5
3x-y=4

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

y=-2+5
y=3

3x+2y=71
y=4+2x

3x+2(4+2x)=71
3x+8+4x=71
7x+8=71
7x=63
x=9

y=4+2(9)
y=4+18
y=22

y=3x+8
x=y

x=3x+8
2x=-8
x=-4
y=-4

x-7y=13
3x-5y=23

x=13+7y
3(13+7y)-5y=23
39+21y-5y=23
39+16y=23
16y=-16
y=-1

x-7(-1)=13
x+7=13
x=6