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)(a − b) = a² − b² to find 33 × 27.
- 2.Use (a + b)² = a² + 2ab + b² to find 37².
- 3.Use (a + b)² = a² + 2ab + b² to find 24².
- 4.Use (a + b)(a − b) = a² − b² to find 24 × 16.
- 5.Use (a + b)(a − b) = a² − b² to find 27 × 13.
- 6.Find the value of x² − 2xy + y² when x = 6 and y = 5.
- 7.Use (a − b)² = a² − 2ab + b² to find 19².
- 8.Use (a + b)(a − b) = a² − b² to find 87 × 73.
- 9.Use (a − b)² = a² − 2ab + b² to find 63².
- 10.Use (a + b)(a − b) = a² − b² to find 102 × 98.
- 11.Use a² − b² = (a + b)(a − b) to find 94² − 59².
- 12.Use (a + b)(a − b) = a² − b² to find 92 × 88.
- 13.Use (a + b)(a − b) = a² − b² to find 71 × 69.
- 14.Use (a + b)² = a² + 2ab + b² to find 29².
- 15.If a + b = 17 and ab = 70, what is a² + b²?
- 16.Use (a + b)(a − b) = a² − b² to find 36 × 24.
- 17.Use a² − b² = (a + b)(a − b) to find 62² − 1².
- 18.If a + b = 3 and ab = 2, what is a² + b²?
- 19.Use (a − b)² = a² − 2ab + b² to find 89².
- 20.Use (a − b)² = a² − 2ab + b² to find 15².
- 21.Use (a + b)² = a² + 2ab + b² to find 13².
- 22.Use (a + b)² = a² + 2ab + b² to find 56².
- 23.Use (a − b)² = a² − 2ab + b² to find 28².
- 24.Use (a + b)² = a² + 2ab + b² to find 91².
- 25.Use (a + b)(a − b) = a² − b² to find 56 × 44.
- 26.Use (a + b)(a − b) = a² − b² to find 91 × 89.
- 27.Use (a + b)² = a² + 2ab + b² to find 49².
- 28.Use (a + b)² = a² + 2ab + b² to find 22².
- 29.Use (a + b)² = a² + 2ab + b² to find 33².
- 30.Find the value of x² − 2xy + y² when x = 4 and y = 2.
- 31.Use (a + b)(a − b) = a² − b² to find 26 × 14.
- 32.If a + b = 10 and ab = 24, what is a² + b²?
- 33.Use a² − b² = (a + b)(a − b) to find 86² − 54².
- 34.Use (a − b)² = a² − 2ab + b² to find 54².
- 35.Use (a + b)² = a² + 2ab + b² to find 108².
- 36.Use a² − b² = (a + b)(a − b) to find 20² − 1².
- 37.If a − b = 4 and ab = 21, what is a² + b²?
- 38.Use (a + b)² = a² + 2ab + b² to find 17².
- 39.Use (a + b)(a − b) = a² − b² to find 108 × 92.
- 40.Use a² − b² = (a + b)(a − b) to find 41² − 14².
Answer key
- 891
- 1369
- 576
- 384
- 351
- 1
- 361
- 6351
- 3969
- 9996
- 5355
- 8096
- 4899
- 841
- 149
- 864
- 3843
- 5
- 7921
- 225
- 169
- 3136
- 784
- 8281
- 2464
- 8099
- 2401
- 484
- 1089
- 4
- 364
- 52
- 4480
- 2916
- 11664
- 399
- 58
- 289
- 9936
- 1485
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