Question

Select the best possible first step to solving the system by first eliminating the x variable.3x − 9y = 6 2x − 11y = 6?

Answer 1

Answer:

x=4/5

y=-2/5

Step-by-step explanation:

We have two equations:

$3\cdotx-9\cdoty=6$

$2\cdotx-11\cdoty=6$

We can eliminate x by making x of equation 1 be equal to x in the equation 2:

$x=2+3\cdoty$

Substitute into equation 2:

$2\cdot(2+3\cdoty)-11\cdoty=6$

Simplify:

$2\cdot2+2\cdot3\cdoty-11\cdoty=6$

$4+6\cdoty-11\cdoty=6$

$-5\cdoty=2$

$y=-2/5$

Substitute back into one of the equations:

$x=2+3\cdot(-2/5)$

$x=2-6/5$

$x=10/5-6/5=4/5$

Answer 2

$\left\{\begin{array}{ccc}3x-9y=6&|divide\ both\ sides\ by\ 3\\2x-11y=6&|divide\ both\ sides\ by\ (-2)\end{array}\right\\\\\underline{+ \left\{\begin{array}{ccc}x-3y=2\\-x+5.5y=-3\end{array}\right}\\.\ \ \ 2.5y=-1$