Solve the following systems by any method.

4x + 7y = 6

9x - 2y = 49

and

3x - y = 4

y = 2x -2

SmartMathMan Apr 30, 2019

#1**+1 **

4x + 7y = 6

9x - 2y = 49

Let's choose to eliminate y.....we can do this by multiplying the first equation by 2 and the second by 7.....do you see why this might work, SMM???.....so we have

8x + 14y = 12

63x - 14y = 343 add these and notice that "y" disappears

71x = 355 divide both sides by 71

x = 5

Can you take it from here and find y ???

3x - y = 4

y = 2x -2 easier than the first one......we have an explicit expression for y......so....sub the second equation into the first for y and we have

3x - [ 2x - 2 ] = 4 simplify

3x - 2x + 2 = 4

x + 2 = 4

x = 2

Sub this into the second equation to find y

CPhill Apr 30, 2019