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 = 5 and y = 1.
- 2.Use a² − b² = (a + b)(a − b) to find 34² − 16².
- 3.Use (a − b)² = a² − 2ab + b² to find 36².
- 4.Use (a + b)² = a² + 2ab + b² to find 17².
- 5.Use (a − b)² = a² − 2ab + b² to find 64².
- 6.Use (a + b)(a − b) = a² − b² to find 57 × 43.
- 7.Use (a + b)(a − b) = a² − b² to find 88 × 72.
- 8.Use (a + b)(a − b) = a² − b² to find 105 × 95.
- 9.Use (a + b)² = a² + 2ab + b² to find 72².
- 10.Use (a − b)² = a² − 2ab + b² to find 19².
- 11.Use (a + b)² = a² + 2ab + b² to find 88².
- 12.Use a² − b² = (a + b)(a − b) to find 37² − 6².
- 13.Use (a + b)² = a² + 2ab + b² to find 105².
- 14.Use (a + b)(a − b) = a² − b² to find 83 × 77.
- 15.Use (a + b)(a − b) = a² − b² to find 36 × 24.
- 16.If a − b = 2 and ab = 48, what is a² + b²?
- 17.Use a² − b² = (a + b)(a − b) to find 35² − 20².
- 18.Use (a − b)² = a² − 2ab + b² to find 16².
- 19.Use (a + b)² = a² + 2ab + b² to find 64².
- 20.Use a² − b² = (a + b)(a − b) to find 24² − 4².
- 21.Use a² − b² = (a + b)(a − b) to find 69² − 54².
- 22.Use (a − b)² = a² − 2ab + b² to find 14².
- 23.Use (a + b)² = a² + 2ab + b² to find 83².
- 24.Use (a − b)² = a² − 2ab + b² to find 77².
- 25.If a − b = 1 and ab = 2, what is a² + b²?
- 26.Use (a − b)² = a² − 2ab + b² to find 33².
- 27.Use (a + b)(a − b) = a² − b² to find 47 × 33.
- 28.Use (a − b)² = a² − 2ab + b² to find 78².
- 29.Use (a + b)² = a² + 2ab + b² to find 95².
- 30.Use (a − b)² = a² − 2ab + b² to find 43².
- 31.Use (a − b)² = a² − 2ab + b² to find 49².
- 32.Use (a − b)² = a² − 2ab + b² to find 39².
- 33.Use (a + b)² = a² + 2ab + b² to find 85².
- 34.Use a² − b² = (a + b)(a − b) to find 32² − 11².
- 35.If a − b = 5 and ab = 6, what is a² + b²?
- 36.Use (a − b)² = a² − 2ab + b² to find 99².
- 37.Use a² − b² = (a + b)(a − b) to find 63² − 54².
- 38.If a + b = 3 and ab = 2, what is a² + b²?
- 39.Use a² − b² = (a + b)(a − b) to find 61² − 28².
- 40.Use (a + b)(a − b) = a² − b² to find 44 × 36.
Answer key
- 36
- 900
- 1296
- 289
- 4096
- 2451
- 6336
- 9975
- 5184
- 361
- 7744
- 1333
- 11025
- 6391
- 864
- 100
- 825
- 256
- 4096
- 560
- 1845
- 196
- 6889
- 5929
- 5
- 1089
- 1551
- 6084
- 9025
- 1849
- 2401
- 1521
- 7225
- 903
- 37
- 9801
- 1053
- 5
- 2937
- 1584
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