Question

Use the elimination method to solve the following system of equations. x+y=1 and x-y=-6

.
The system has a single solution. The solution set is (X,Y)
​(Type an ordered​ pair, using integers or​ fractions.)

B.
There are infinitely many solutions. The solution set is (Type an equation. Type your answer in standard​ form.)

C.The solution set is the empty set.

Answer 1

$\bf \begin{array}{llll} x+y=1&\times(-1)\implies &\begin{matrix} -x \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~-y&=-1\\ x-y=-6&&\begin{matrix} x \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~~~ -y&=-6\\ \cline{3-4}\\ &&~\hfill -2y&=-7 \end{array} \\\\\\ y=\cfrac{-7}{-2}\implies \blacktriangleright y=\cfrac{7}{2} \blacktriangleleft \\\\[-0.35em] ~\dotfill$

$\bf \stackrel{\textit{substituting on the 1st equation}}{x+\left( \cfrac{7}{2} \right)=1\implies x=1-\cfrac{7}{2}}\implies \blacktriangleright x=-\cfrac{5}{2} \blacktriangleleft \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill \left(-\frac{5}{2}~~,~~\frac{7}{2} \right)~\hfill$