Question

How to solv using elimination:
9x-2y=-21
2x+3y=16

Answer 1

9x - 2y = -21 /·3
2x + 3y = 16 /·2

27x - 6y = -63
4x + 6y = 32
---------------------
31x = -31 /:31
x = -1

2x + 3y = 16 ⇒ 3y = 16 - 2x
3y = 16 - 2 · (-1)
3y = 18 /:3
y = 6
Ans.:
x = -1
y = 6

Answer 2

`\begin{cases} 9x-2y=-21 /*3\\ 2x+3y=16 /*2 \end{cases}\\ \\\begin{cases} 27x-6y=-63\\ 4x+6y=32 \end{cases}\\--------- \\31x =-31/:31\\ \\x=-1`


`9*(-1)-2y=-21\\ \\-2y=-21+9\\ \\-2y=-12/:(-2)\\ \\y=6\\ \\\begin{cases} x=-1\\ y=6 \end{cases}`