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Help with maths homework please!

Solve each of the following pairs of simultaneous equations by first changing the subject of one of the equations to give an equal term. Then, by addition or subtraction, eliminate the equal term.

2) 3x + y = 9
4 x + 5y = 23
4) 4x + 3y = 37
2x + y = 17
6) 10 x - 3y = 19
x + 2y = 18

I may delete my brainly account that's why I'm giving so many points :D but also I really need this to be done and I have no idea how to solve it.

Thank you

Sagot :

2)
3x + y =  9 is equivalent to -15x - 5y = -45 by multiplying both sides by -5

 -15x  - 5y = -45
+  4x + 5y =  23
 -11x + 0y = -22

-11x = -22
x = 2

3(2) + y = 9
6 + y = 9
y = 3

4)
2x + y = 17 is equivalent to -6x - 3y = -51 by multiplying both sides by -3

     4x + 3y =  37
+ (-6x  - 3y = -51)
    -2x + 0y = -14

-2x = -14
x = 7

4(7) + 3y = 37
28 + 3y = 37
3y = 9
y = 3

6)
x + 2y = 18 is equivalent to -10x - 20y = -180 by multiplying both sides by -10

     10x -   3y =   19
+ (-10x - 20y = -180)
      0x  - 23y = -161

-23y = -161
y = 7

10x - 3(7) = 19
10x - 21 = 19
10x = 40
x = 4

I hope this helped ^_^

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