How to solve this
2x+y=-5
2x+3y=9


Sagot :

Solve by substiution:

Equation A:  2x + y = -5
Equation B:  2x + 3y = 9

Transform Equation A to slope-intercept form, y = mx + b
2x + y = -5
y = -2x - 5    ⇒  Equation C

Substitute -2x -5 to y in Equation B ⇒ 2x + 3y = 9
2x + 3 (-2x-5) = 9
2x - 6x - 15 = 9
-4x = 9 + 15
-4x = 24
-4x/-4 = 24/-4
x = - 6

Substitute 6 to x in Equation C  
⇒ y = -2x - 5

y = -2(-6) - 5
y = +12 - 5
y = 7

x = - 6   and  y = 7

The solution is (-6, 7).
The linear equation pair has different slopes, -2 and -2/3.
The lines are intersecting.
The system is consistent and independent.