Question

x-y=1,ax+y=2 has unique solution then a=1 or a=-1​

Answer 1

Answer:

a = 1

Step-by-step explanation:

$\textit{The general form for a pair of linear equations in two variables x and y is} \\ a_1x+b_1y+c_1=0 \\ a_2x+b_2y+c_2=0 \\\\ \textit{condition for unique solution} : \\ \\ \frac{a_1}{a_2} \ne \frac{b_1}{b_2} \\\\ here,\\ a_1=1,b_1=-1 \\a_2=a,b_2=1 \\\\ => \frac{1}{a} \ne\frac{-1}{1} \\\\ =>a \ne -1 \\\\ \textbf{so,a can be 1}$

hope it helps..!