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.If a + b = 23 and ab = 132, what is a² + b²?
- 2.Use (a − b)² = a² − 2ab + b² to find 56².
- 3.Use (a + b)(a − b) = a² − b² to find 78 × 62.
- 4.Use (a + b)² = a² + 2ab + b² to find 65².
- 5.Use (a − b)² = a² − 2ab + b² to find 99².
- 6.Use (a + b)² = a² + 2ab + b² to find 13².
- 7.Use (a + b)(a − b) = a² − b² to find 89 × 71.
- 8.Use a² − b² = (a + b)(a − b) to find 83² − 29².
- 9.Use (a − b)² = a² − 2ab + b² to find 11².
- 10.Use (a + b)² = a² + 2ab + b² to find 96².
- 11.Use (a + b)² = a² + 2ab + b² to find 25².
- 12.Use (a − b)² = a² − 2ab + b² to find 91².
- 13.Use (a + b)² = a² + 2ab + b² to find 11².
- 14.If a + b = 9 and ab = 14, what is a² + b²?
- 15.Use (a − b)² = a² − 2ab + b² to find 61².
- 16.Use a² − b² = (a + b)(a − b) to find 64² − 44².
- 17.Use (a − b)² = a² − 2ab + b² to find 55².
- 18.Find the value of x² + 2xy + y² when x = 14 and y = 4.
- 19.If a − b = 7 and ab = 60, what is a² + b²?
- 20.Use (a − b)² = a² − 2ab + b² to find 52².
- 21.Use (a − b)² = a² − 2ab + b² to find 94².
- 22.If a + b = 14 and ab = 45, what is a² + b²?
- 23.Use (a + b)(a − b) = a² − b² to find 28 × 12.
- 24.Use (a − b)² = a² − 2ab + b² to find 97².
- 25.Use (a + b)² = a² + 2ab + b² to find 75².
- 26.Find the value of x² − y² when x = 15 and y = 11.
- 27.Use (a − b)² = a² − 2ab + b² to find 96².
- 28.If a − b = 3 and ab = 10, what is a² + b²?
- 29.Use (a − b)² = a² − 2ab + b² to find 92².
- 30.Use (a + b)(a − b) = a² − b² to find 103 × 97.
- 31.Find the value of x² − y² when x = 12 and y = 7.
- 32.Use (a + b)² = a² + 2ab + b² to find 69².
- 33.Use a² − b² = (a + b)(a − b) to find 77² − 62².
- 34.Use (a − b)² = a² − 2ab + b² to find 49².
- 35.Use (a + b)(a − b) = a² − b² to find 77 × 63.
- 36.Use (a + b)² = a² + 2ab + b² to find 46².
- 37.If a + b = 9 and ab = 20, what is a² + b²?
- 38.If a + b = 3 and ab = 2, what is a² + b²?
- 39.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 40.Use a² − b² = (a + b)(a − b) to find 58² − 2².
Answer key
- 265
- 3136
- 4836
- 4225
- 9801
- 169
- 6319
- 6048
- 121
- 9216
- 625
- 8281
- 121
- 53
- 3721
- 2160
- 3025
- 324
- 169
- 2704
- 8836
- 106
- 336
- 9409
- 5625
- 104
- 9216
- 29
- 8464
- 9991
- 95
- 4761
- 2085
- 2401
- 4851
- 2116
- 41
- 5
- 1591
- 3360
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