CBSE Guess > Papers > Important Questions > Class XII > 2010 > Maths > Mathematics By Mr. Manish Lekhwar

CBSE CLASS XII

Q. 17.

If A = and (A + B) 2 = A2 + B2, find a and b.

Q. 18.

If A = , then prove that A4 = 0, where 0 stands for a null matrix.

Q. 19.

If A = , then show that A3 = 4A.

Q. 20.

If A = , then prove that A³ A² + 7A + 2I = 0.

Q. 21.

Find each of the following:

1. (A + C)’
2. 2A’ – B’
3. (A + B + C)’

Q. 22. Prove that any square matrix can be expressed as the sum of a symmetric and a skew symmetric matrix.

Q. 23. A store has in stock 240 shirts, 192 jerseys and 384 trousers. The selling price of one shirt, one jersey and one trouser are Rs 350, Rs 500 and Rs 400 respectively. Using matrices, find the money the store owner will receive by selling all the items of his stock.
[Ans. Rs 333600]

Q. 24. Three shopkeepers A, B and C go to a store to buy stationary items. A purchases 12 dozen notebooks, 6 dozen pens and 10 dozen pencils; B purchases 20 dozen notebooks, 10 dozen pens and 15 dozen pencils and C purchases 10 dozen notebooks, 10 dozen pens and 25 dozen pencils. If per dozen rates of notebooks, pen and pencil are Rs 72, Rs 48 and Rs 18
respectively, use matrix multiplication to calculate bill of each.
[Ans. Rs 1332, Rs 2190 and Rs 1650]

Paper By Mr. Manish Lekhwar
Email Id :[email protected]