Question

Use the above formulae to fill proper terms in the following boxes.

1. (x + 2y)² = x² + ___ + 4y²

2. (2x – 5y)² = __ – 20xy + __

3. (101)² = (100 + 1)² = ___+ ___ + 1² = ___

4. (98)² = (100 – 2)² = 10000 – ___ + ___ = ___

5. (5m + 3n) (5m – 3n) = ___ – ___ = ___ - ___

Answer 1

1. (x + 2y)² = x² + 4xy + 4y² 

2. (2x – 5y)² = 4x² – 20xy + 25y² 

3. (101)² = (100 + 1)² = 10000 + 200 + 1² = 10201 

4. (98)² = (100 – 2)² = 10000 – 400 + 4 = 9604 

5. (5m + 3n) (5m – 3n) = (5m)² – (3n)² = 25m² – 9n²