Class 8 Maths Worksheet: Algebraic Identities
The method (Split into easy parts): (a + b)² = a² + 2ab + b². (a − b)² = a² − 2ab + b². (a + b)(a − b) = a² − b²; so a² − b² = (a + b)(a − b). a² + b² = (a + b)² − 2ab = (a − b)² + 2ab.
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- 1.Find the value of x² + 2xy + y² when x = 8 and y = 1.
- 2.Use a² − b² = (a + b)(a − b) to find 24² − 2².
- 3.If a − b = 1 and ab = 90, what is a² + b²?
- 4.Use a² − b² = (a + b)(a − b) to find 29² − 13².
- 5.Find the value of x² − y² when x = 9 and y = 1.
- 6.Find the value of x² + 2xy + y² when x = 14 and y = 12.
- 7.Find the value of x² + 2xy + y² when x = 8 and y = 5.
- 8.Use (a + b)² = a² + 2ab + b² to find 85².
- 9.Use a² − b² = (a + b)(a − b) to find 61² − 18².
- 10.If a + b = 13 and ab = 40, what is a² + b²?
- 11.Use a² − b² = (a + b)(a − b) to find 97² − 75².
- 12.Use a² − b² = (a + b)(a − b) to find 82² − 79².
- 13.Use a² − b² = (a + b)(a − b) to find 23² − 10².
- 14.Use (a + b)(a − b) = a² − b² to find 81 × 79.
- 15.Find the value of x² − y² when x = 6 and y = 2.
- 16.Use (a + b)(a − b) = a² − b² to find 106 × 94.
- 17.Use (a + b)² = a² + 2ab + b² to find 34².
- 18.Use (a − b)² = a² − 2ab + b² to find 27².
- 19.Use (a + b)² = a² + 2ab + b² to find 35².
- 20.Use (a + b)² = a² + 2ab + b² to find 42².
- 21.Use a² − b² = (a + b)(a − b) to find 36² − 26².
- 22.Use (a + b)(a − b) = a² − b² to find 31 × 29.
- 23.Use (a + b)² = a² + 2ab + b² to find 18².
- 24.Use a² − b² = (a + b)(a − b) to find 25² − 24².
- 25.Use (a + b)(a − b) = a² − b² to find 23 × 17.
- 26.Use (a + b)² = a² + 2ab + b² to find 27².
- 27.Use (a − b)² = a² − 2ab + b² to find 73².
- 28.Use (a − b)² = a² − 2ab + b² to find 82².
- 29.Use (a + b)² = a² + 2ab + b² to find 12².
- 30.Use (a − b)² = a² − 2ab + b² to find 99².
- 31.Use (a + b)(a − b) = a² − b² to find 36 × 24.
- 32.Use a² − b² = (a + b)(a − b) to find 67² − 25².
- 33.Use (a + b)(a − b) = a² − b² to find 57 × 43.
- 34.Use (a − b)² = a² − 2ab + b² to find 61².
- 35.Find the value of x² − 2xy + y² when x = 10 and y = 4.
- 36.If a − b = 1 and ab = 2, what is a² + b²?
- 37.Use (a + b)² = a² + 2ab + b² to find 76².
- 38.Use a² − b² = (a + b)(a − b) to find 25² − 22².
- 39.Use (a + b)² = a² + 2ab + b² to find 14².
- 40.Use (a + b)(a − b) = a² − b² to find 62 × 58.
Answer key
- 81
- 572
- 181
- 672
- 80
- 676
- 169
- 7225
- 3397
- 89
- 3784
- 483
- 429
- 6399
- 32
- 9964
- 1156
- 729
- 1225
- 1764
- 620
- 899
- 324
- 49
- 391
- 729
- 5329
- 6724
- 144
- 9801
- 864
- 3864
- 2451
- 3721
- 36
- 5
- 5776
- 141
- 196
- 3596
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