Question

A shopkeeper has 3 varieties of pens ‘A’, ‘B’ and ‘C’. Meenu purchased 1 pen of each variety for a total of ₹ 21. Jeevan purchased 4 pens of ‘A’ variety, 3 pens of ‘B’ variety and 2 pens of ‘C’ variety for ₹ 60. While Shikha purchased 6 pens of ‘A’ variety, 2 pens of ‘B’ variety and 3 pens of ‘C’ variety for ₹ 70. Using matrix method, find cost of each variety of pen.

Answer 1

Let the cost of varieties of pens A, B and C be x, y, and z respectively.

From question,

The given system of linear equation in matrix equation is as follows

AX = B, where

Now,

Now from (i) X = A^-1B

⇒ Cost of pen A = ₹ 5

Cost of pen B = ₹ 8

Cost of pen C = ₹ 8