Find 3 examples where the product of two numbers remains unchanged when one of them is increased Class 8

Find 3 examples where the product of two numbers remains unchanged when one of them is increased Class 8

Question 1.

Find 3 examples where the product of two numbers remains unchanged when one of them is increased by 2 and the other is decreased by 4. Class 8

Solution:

Example 1: 1 × 6 = 6 and (1 + 2)

(6 - 4) = 3 × 2 = 6

Example 2 : 2 × 8 = 16 and (2 + 2)

(8 - 4) = 4 × 4 = 16

Example 3 : 3 × 10 = 30 and (3 + 2)

(10 — 4) = 5 × 6 = 30

Question 2.

Expand (i) (a + ab - 3b²) (4 + b), and (ii) (4y + 7) (y + 11z - 3). Class 8

Solution:

(i) (a + ab - 3b²>) (4 + b)

= a (4 + b) + ab (4 + b) - 3b²(4 + b)

= 4a + ab + 4ab + ab² - 12b² — 3b³

= 4a + 5ab + ab² - 12b² - 3b³

(ii) (4y + 7) (y + 11z - 3)

= 4y (y + 11z - 3) + 7 (y + 11z - 3)

= 4y² + 44yz - 12y + 7y + 77z — 21

= 4y² + 44yz - 5y + 77z — 21