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 − y² when x = 12 and y = 8.
- 2.If a + b = 7 and ab = 12, what is a² + b²?
- 3.Use (a − b)² = a² − 2ab + b² to find 83².
- 4.Use (a + b)² = a² + 2ab + b² to find 33².
- 5.Find the value of x² − 2xy + y² when x = 8 and y = 1.
- 6.If a + b = 13 and ab = 22, what is a² + b²?
- 7.Use (a + b)² = a² + 2ab + b² to find 32².
- 8.Use (a − b)² = a² − 2ab + b² to find 21².
- 9.Use (a − b)² = a² − 2ab + b² to find 14².
- 10.Use (a − b)² = a² − 2ab + b² to find 16².
- 11.Use (a − b)² = a² − 2ab + b² to find 98².
- 12.Use (a + b)(a − b) = a² − b² to find 51 × 49.
- 13.Use (a − b)² = a² − 2ab + b² to find 55².
- 14.Find the value of x² − 2xy + y² when x = 10 and y = 6.
- 15.Use (a + b)(a − b) = a² − b² to find 91 × 89.
- 16.Use (a + b)² = a² + 2ab + b² to find 107².
- 17.Use (a − b)² = a² − 2ab + b² to find 59².
- 18.Use a² − b² = (a + b)(a − b) to find 62² − 22².
- 19.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 20.Use a² − b² = (a + b)(a − b) to find 64² − 34².
- 21.Use a² − b² = (a + b)(a − b) to find 70² − 26².
- 22.Use (a + b)² = a² + 2ab + b² to find 95².
- 23.Use a² − b² = (a + b)(a − b) to find 55² − 39².
- 24.Use a² − b² = (a + b)(a − b) to find 89² − 71².
- 25.Use (a + b)(a − b) = a² − b² to find 41 × 39.
- 26.Use (a − b)² = a² − 2ab + b² to find 45².
- 27.Use (a + b)² = a² + 2ab + b² to find 13².
- 28.Find the value of x² + 2xy + y² when x = 14 and y = 13.
- 29.If a − b = 1 and ab = 30, what is a² + b²?
- 30.If a + b = 12 and ab = 27, what is a² + b²?
- 31.Find the value of x² + 2xy + y² when x = 6 and y = 3.
- 32.If a + b = 19 and ab = 84, what is a² + b²?
- 33.If a + b = 6 and ab = 5, what is a² + b²?
- 34.Use (a + b)² = a² + 2ab + b² to find 34².
- 35.Use (a − b)² = a² − 2ab + b² to find 86².
- 36.If a + b = 15 and ab = 54, what is a² + b²?
- 37.Use (a − b)² = a² − 2ab + b² to find 49².
- 38.Use (a + b)² = a² + 2ab + b² to find 25².
- 39.Use a² − b² = (a + b)(a − b) to find 77² − 29².
- 40.Use a² − b² = (a + b)(a − b) to find 65² − 47².
Answer key
- 80
- 25
- 6889
- 1089
- 49
- 125
- 1024
- 441
- 196
- 256
- 9604
- 2499
- 3025
- 16
- 8099
- 11449
- 3481
- 3360
- 2484
- 2940
- 4224
- 9025
- 1504
- 2880
- 1599
- 2025
- 169
- 729
- 61
- 90
- 81
- 193
- 26
- 1156
- 7396
- 117
- 2401
- 625
- 5088
- 2016
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