Question

como resolver este sistema de primeiro grau 4x + 5y= 12 2x - y = -1

Answer 1

4x + 5y = 12
2x - y = - 1

2x - y = - 1
-y = -1 -2x .(-1)
y = 1 + 2x ← importante.

4x + 5y = 12
4x + 5(1+2x) = 12
4x + 5 + 10x = 12
14x + 5 = 12
14x = 12 - 5
14x = 7
x = 7/14 = 1/2

y = 1 + 2x
y = 1 + 2 . 1/2
y = 1 + 1
y = 2

x = 1/2
y = 2

Answer 2

Y=2
X=1/2
y=2x+1
4x+5(2x=1)=12
14x+5=12
14x=7
x=1/2
y=1+1