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 = 2.
- 2.Find the value of x² − 2xy + y² when x = 4 and y = 2.
- 3.Use (a + b)² = a² + 2ab + b² to find 12².
- 4.Use a² − b² = (a + b)(a − b) to find 23² − 7².
- 5.If a + b = 12 and ab = 27, what is a² + b²?
- 6.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 7.Use (a + b)² = a² + 2ab + b² to find 15².
- 8.Use (a + b)² = a² + 2ab + b² to find 101².
- 9.Use (a + b)(a − b) = a² − b² to find 44 × 36.
- 10.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 11.Use a² − b² = (a + b)(a − b) to find 59² − 41².
- 12.Use (a + b)(a − b) = a² − b² to find 93 × 87.
- 13.Use (a + b)(a − b) = a² − b² to find 61 × 59.
- 14.Find the value of x² − y² when x = 12 and y = 2.
- 15.If a − b = 1 and ab = 90, what is a² + b²?
- 16.If a − b = 4 and ab = 60, what is a² + b²?
- 17.Use (a − b)² = a² − 2ab + b² to find 74².
- 18.Use (a + b)² = a² + 2ab + b² to find 92².
- 19.Use a² − b² = (a + b)(a − b) to find 50² − 9².
- 20.Use a² − b² = (a + b)(a − b) to find 85² − 6².
- 21.Use a² − b² = (a + b)(a − b) to find 72² − 40².
- 22.If a + b = 16 and ab = 55, what is a² + b²?
- 23.If a − b = 2 and ab = 120, what is a² + b²?
- 24.Find the value of x² − y² when x = 11 and y = 8.
- 25.Use a² − b² = (a + b)(a − b) to find 99² − 70².
- 26.Use (a + b)² = a² + 2ab + b² to find 11².
- 27.Use (a + b)(a − b) = a² − b² to find 72 × 68.
- 28.Use a² − b² = (a + b)(a − b) to find 75² − 65².
- 29.Use (a + b)(a − b) = a² − b² to find 103 × 97.
- 30.Use a² − b² = (a + b)(a − b) to find 36² − 19².
- 31.If a − b = 3 and ab = 54, what is a² + b²?
- 32.If a + b = 5 and ab = 6, what is a² + b²?
- 33.Use (a + b)(a − b) = a² − b² to find 51 × 49.
- 34.Use (a + b)² = a² + 2ab + b² to find 71².
- 35.Use a² − b² = (a + b)(a − b) to find 81² − 53².
- 36.Use (a + b)(a − b) = a² − b² to find 36 × 24.
- 37.Use (a − b)² = a² − 2ab + b² to find 21².
- 38.Use (a − b)² = a² − 2ab + b² to find 13².
- 39.Use (a − b)² = a² − 2ab + b² to find 98².
- 40.Use (a − b)² = a² − 2ab + b² to find 23².
Answer key
- 9
- 4
- 144
- 480
- 90
- 2484
- 225
- 10201
- 1584
- 25
- 1800
- 8091
- 3599
- 140
- 181
- 136
- 5476
- 8464
- 2419
- 7189
- 3584
- 146
- 244
- 57
- 4901
- 121
- 4896
- 1400
- 9991
- 935
- 117
- 13
- 2499
- 5041
- 3752
- 864
- 441
- 169
- 9604
- 529
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