What is the value of the x variable in the solution to the following system of equations?
2x + 3y = 4
x - 2y = -5

Question

What is the value of the x variable in the solution to the following system of equations?
2x + 3y = 4
x - 2y = -5

anonymous · Answer

Q1 :  x - 2y = -5  =>  2y = x +5  =>   y = (x+5)/2
Q2 :  2x + 3(y) = 4   

Put Q1 into Q2 => 2x + 3*[(x+5)/2] = 4  
times 2 to both sides ==> 2 * [2x + 3((x+5)/2)] = (4) * 2

=>  4x + 3(x+5) = 8
=>  4x + 3x +15 = 8
=>  7x = 8-15
=>  x = -7/7
=>  x = -1

verification if x = -1
Q1 :   (-1) -2y = -5  => 4 = 2y => y = 2
Q2 :   2(-1) + 3(2) = 4 => -2 +6 = 4  ==> correct !