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 = 14 and y = 1.
- 2.If a + b = 3 and ab = 2, what is a² + b²?
- 3.Use (a − b)² = a² − 2ab + b² to find 91².
- 4.Find the value of x² − 2xy + y² when x = 3 and y = 1.
- 5.Use a² − b² = (a + b)(a − b) to find 35² − 12².
- 6.Use a² − b² = (a + b)(a − b) to find 97² − 62².
- 7.Use (a + b)(a − b) = a² − b² to find 88 × 72.
- 8.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 9.Use (a − b)² = a² − 2ab + b² to find 67².
- 10.Use (a + b)² = a² + 2ab + b² to find 106².
- 11.If a − b = 2 and ab = 3, what is a² + b²?
- 12.Use (a + b)² = a² + 2ab + b² to find 43².
- 13.If a − b = 6 and ab = 16, what is a² + b²?
- 14.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 15.Use a² − b² = (a + b)(a − b) to find 24² − 4².
- 16.If a − b = 1 and ab = 2, what is a² + b²?
- 17.If a + b = 14 and ab = 40, what is a² + b²?
- 18.Find the value of x² − 2xy + y² when x = 15 and y = 12.
- 19.Use (a − b)² = a² − 2ab + b² to find 17².
- 20.Use (a + b)(a − b) = a² − b² to find 72 × 68.
- 21.If a − b = 3 and ab = 54, what is a² + b²?
- 22.Use (a + b)² = a² + 2ab + b² to find 57².
- 23.Use (a + b)(a − b) = a² − b² to find 63 × 57.
- 24.Use (a − b)² = a² − 2ab + b² to find 85².
- 25.Find the value of x² − y² when x = 6 and y = 3.
- 26.Use (a − b)² = a² − 2ab + b² to find 84².
- 27.Find the value of x² + 2xy + y² when x = 7 and y = 2.
- 28.If a − b = 3 and ab = 10, what is a² + b²?
- 29.Use (a + b)(a − b) = a² − b² to find 37 × 23.
- 30.Use (a + b)² = a² + 2ab + b² to find 97².
- 31.Use a² − b² = (a + b)(a − b) to find 47² − 27².
- 32.Find the value of x² − y² when x = 12 and y = 9.
- 33.If a + b = 8 and ab = 7, what is a² + b²?
- 34.Use a² − b² = (a + b)(a − b) to find 93² − 63².
- 35.Use (a + b)(a − b) = a² − b² to find 106 × 94.
- 36.Find the value of x² + 2xy + y² when x = 4 and y = 2.
- 37.Find the value of x² − 2xy + y² when x = 4 and y = 2.
- 38.If a + b = 13 and ab = 30, what is a² + b²?
- 39.Use (a + b)² = a² + 2ab + b² to find 51².
- 40.If a + b = 8 and ab = 15, what is a² + b²?
Answer key
- 169
- 5
- 8281
- 4
- 1081
- 5565
- 6336
- 399
- 4489
- 11236
- 10
- 1849
- 68
- 1591
- 560
- 5
- 116
- 9
- 289
- 4896
- 117
- 3249
- 3591
- 7225
- 27
- 7056
- 81
- 29
- 851
- 9409
- 1480
- 63
- 50
- 4680
- 9964
- 36
- 4
- 109
- 2601
- 34
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