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.Use (a + b)² = a² + 2ab + b² to find 99².
- 2.Use (a + b)² = a² + 2ab + b² to find 57².
- 3.Use (a + b)² = a² + 2ab + b² to find 67².
- 4.If a + b = 7 and ab = 12, what is a² + b²?
- 5.If a − b = 2 and ab = 15, what is a² + b²?
- 6.Use a² − b² = (a + b)(a − b) to find 38² − 9².
- 7.Find the value of x² − 2xy + y² when x = 14 and y = 9.
- 8.Use (a + b)(a − b) = a² − b² to find 26 × 14.
- 9.Find the value of x² − 2xy + y² when x = 8 and y = 3.
- 10.Find the value of x² − y² when x = 3 and y = 2.
- 11.If a + b = 16 and ab = 63, what is a² + b²?
- 12.Use (a + b)(a − b) = a² − b² to find 84 × 76.
- 13.Use a² − b² = (a + b)(a − b) to find 97² − 11².
- 14.Use (a − b)² = a² − 2ab + b² to find 94².
- 15.Use a² − b² = (a + b)(a − b) to find 68² − 2².
- 16.Use (a + b)(a − b) = a² − b² to find 77 × 63.
- 17.Use (a + b)(a − b) = a² − b² to find 45 × 35.
- 18.Use (a + b)(a − b) = a² − b² to find 68 × 52.
- 19.Find the value of x² − y² when x = 14 and y = 1.
- 20.If a + b = 19 and ab = 88, what is a² + b²?
- 21.Find the value of x² + 2xy + y² when x = 9 and y = 4.
- 22.Use (a + b)² = a² + 2ab + b² to find 83².
- 23.If a − b = 5 and ab = 36, what is a² + b²?
- 24.Use (a − b)² = a² − 2ab + b² to find 19².
- 25.If a − b = 5 and ab = 24, what is a² + b²?
- 26.Use (a + b)² = a² + 2ab + b² to find 76².
- 27.Use (a + b)² = a² + 2ab + b² to find 43².
- 28.Use (a + b)² = a² + 2ab + b² to find 14².
- 29.Find the value of x² + 2xy + y² when x = 6 and y = 4.
- 30.Use a² − b² = (a + b)(a − b) to find 85² − 6².
- 31.Use (a − b)² = a² − 2ab + b² to find 69².
- 32.Use (a + b)(a − b) = a² − b² to find 44 × 36.
- 33.Use a² − b² = (a + b)(a − b) to find 24² − 6².
- 34.Use (a − b)² = a² − 2ab + b² to find 64².
- 35.If a + b = 8 and ab = 15, what is a² + b²?
- 36.Use (a + b)² = a² + 2ab + b² to find 15².
- 37.Use (a − b)² = a² − 2ab + b² to find 17².
- 38.Use a² − b² = (a + b)(a − b) to find 95² − 21².
- 39.If a − b = 1 and ab = 2, what is a² + b²?
- 40.Use a² − b² = (a + b)(a − b) to find 88² − 70².
Answer key
- 9801
- 3249
- 4489
- 25
- 34
- 1363
- 25
- 364
- 25
- 5
- 130
- 6384
- 9288
- 8836
- 4620
- 4851
- 1575
- 3536
- 195
- 185
- 169
- 6889
- 97
- 361
- 73
- 5776
- 1849
- 196
- 100
- 7189
- 4761
- 1584
- 540
- 4096
- 34
- 225
- 289
- 8584
- 5
- 2844
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