Question

Solve the system of equations using substitution. −2x + y = 3.5
−2y = 3x

Answer 1

`\huge\boxed{x=-1;\ y=-1.5}`

Explanation:

`\left\{\begin{array}{ccc}-2x+y=3.5\\-2y=3x&\text{divide both sides by (-2)}\end{array}\right\\\left\{\begin{array}{ccc}-2x+y=3.5&(1)\\y=-1.5x&(2)\end{array}\right\\\\\\\text{Substitute (2) to 1):}\\-2x+(-1.5x)=3.5\\-2x-1.5x=3.5\qquad\text{combine like terms}\\-3.5x=3.5\qquad\text{divide both sides by (-3.5)}\\(-3.5x)/(-3.5)=(3.5)/(-3.5)\\\boxed{x=-1}\\\\\text{Substitute it to (2):}\\y=1.5(-1)\\\boxed{y=-1.5}`