What is the solution (x,y) of 3x+1y=7 and 1x-1y=2?

A. (9 / 4,1 / 4)

Step 1: Identify the concept: linear equations by determinants. Step 2: By Cramer's rule, a non-zero determinant gives a unique solution. Calculation gives x=9/4, y=1/4. Step 3: Exam tip: A non-zero coefficient determinant means a unique solution.

Step 1: अवधारणा linear equations by determinants है। Step 2: Cramer's rule से determinant non-zero होने पर unique solution मिलता है। Calculation से x=9/4, y=1/4। Step 3: याद रखें: Coefficient determinant zero नहीं हो तो solution unique होता है।