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)² = a² + 2ab + b² to find 31².
- 2.Use a² − b² = (a + b)(a − b) to find 65² − 56².
- 3.If a + b = 16 and ab = 63, what is a² + b²?
- 4.Find the value of x² − 2xy + y² when x = 5 and y = 1.
- 5.Use (a − b)² = a² − 2ab + b² to find 12².
- 6.Use (a + b)² = a² + 2ab + b² to find 75².
- 7.If a + b = 11 and ab = 10, what is a² + b²?
- 8.Use (a + b)² = a² + 2ab + b² to find 83².
- 9.Use a² − b² = (a + b)(a − b) to find 53² − 20².
- 10.Use a² − b² = (a + b)(a − b) to find 95² − 53².
- 11.Find the value of x² − y² when x = 9 and y = 2.
- 12.Find the value of x² − y² when x = 12 and y = 5.
- 13.Use a² − b² = (a + b)(a − b) to find 88² − 61².
- 14.Use (a + b)² = a² + 2ab + b² to find 81².
- 15.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 16.Use (a + b)² = a² + 2ab + b² to find 39².
- 17.Use a² − b² = (a + b)(a − b) to find 65² − 32².
- 18.Use a² − b² = (a + b)(a − b) to find 66² − 2².
- 19.Use (a + b)(a − b) = a² − b² to find 109 × 91.
- 20.Use a² − b² = (a + b)(a − b) to find 77² − 43².
- 21.Use (a + b)² = a² + 2ab + b² to find 106².
- 22.Use a² − b² = (a + b)(a − b) to find 43² − 8².
- 23.Use (a + b)(a − b) = a² − b² to find 93 × 87.
- 24.Use a² − b² = (a + b)(a − b) to find 33² − 18².
- 25.Use a² − b² = (a + b)(a − b) to find 86² − 58².
- 26.Find the value of x² − y² when x = 15 and y = 10.
- 27.Use (a + b)² = a² + 2ab + b² to find 14².
- 28.Use a² − b² = (a + b)(a − b) to find 43² − 40².
- 29.Find the value of x² − 2xy + y² when x = 3 and y = 2.
- 30.Use (a + b)(a − b) = a² − b² to find 76 × 64.
- 31.Find the value of x² + 2xy + y² when x = 8 and y = 6.
- 32.Find the value of x² + 2xy + y² when x = 11 and y = 1.
- 33.Use (a − b)² = a² − 2ab + b² to find 21².
- 34.If a + b = 3 and ab = 2, what is a² + b²?
- 35.Use (a + b)(a − b) = a² − b² to find 37 × 23.
- 36.Use (a − b)² = a² − 2ab + b² to find 31².
- 37.Use (a − b)² = a² − 2ab + b² to find 84².
- 38.Use (a + b)² = a² + 2ab + b² to find 59².
- 39.Use (a + b)² = a² + 2ab + b² to find 29².
- 40.Use (a + b)(a − b) = a² − b² to find 23 × 17.
Answer key
- 961
- 1089
- 130
- 16
- 144
- 5625
- 101
- 6889
- 2409
- 6216
- 77
- 119
- 4023
- 6561
- 875
- 1521
- 3201
- 4352
- 9919
- 4080
- 11236
- 1785
- 8091
- 765
- 4032
- 125
- 196
- 249
- 1
- 4864
- 196
- 144
- 441
- 5
- 851
- 961
- 7056
- 3481
- 841
- 391
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