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 = 4.
- 2.Use (a + b)(a − b) = a² − b² to find 72 × 68.
- 3.Use (a − b)² = a² − 2ab + b² to find 91².
- 4.Use a² − b² = (a + b)(a − b) to find 49² − 10².
- 5.Use (a + b)² = a² + 2ab + b² to find 54².
- 6.Use a² − b² = (a + b)(a − b) to find 60² − 29².
- 7.Use (a + b)(a − b) = a² − b² to find 107 × 93.
- 8.Use (a + b)² = a² + 2ab + b² to find 25².
- 9.Find the value of x² + 2xy + y² when x = 8 and y = 4.
- 10.Find the value of x² − 2xy + y² when x = 4 and y = 3.
- 11.Use (a − b)² = a² − 2ab + b² to find 85².
- 12.Use (a − b)² = a² − 2ab + b² to find 89².
- 13.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 14.Use (a − b)² = a² − 2ab + b² to find 79².
- 15.If a + b = 10 and ab = 21, what is a² + b²?
- 16.Use (a + b)(a − b) = a² − b² to find 52 × 48.
- 17.If a + b = 9 and ab = 18, what is a² + b²?
- 18.Find the value of x² + 2xy + y² when x = 8 and y = 7.
- 19.Use (a + b)² = a² + 2ab + b² to find 29².
- 20.Use (a + b)² = a² + 2ab + b² to find 56².
- 21.Find the value of x² + 2xy + y² when x = 15 and y = 5.
- 22.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 23.Use a² − b² = (a + b)(a − b) to find 55² − 44².
- 24.If a + b = 9 and ab = 20, what is a² + b²?
- 25.Use (a + b)(a − b) = a² − b² to find 97 × 83.
- 26.Use a² − b² = (a + b)(a − b) to find 31² − 4².
- 27.Use a² − b² = (a + b)(a − b) to find 21² − 1².
- 28.Use (a + b)² = a² + 2ab + b² to find 48².
- 29.Use (a + b)² = a² + 2ab + b² to find 85².
- 30.Use (a + b)(a − b) = a² − b² to find 85 × 75.
- 31.Use (a − b)² = a² − 2ab + b² to find 99².
- 32.Use (a + b)(a − b) = a² − b² to find 63 × 57.
- 33.Use (a + b)(a − b) = a² − b² to find 93 × 87.
- 34.Find the value of x² + 2xy + y² when x = 14 and y = 5.
- 35.Find the value of x² − y² when x = 4 and y = 3.
- 36.Use (a − b)² = a² − 2ab + b² to find 59².
- 37.Use (a + b)² = a² + 2ab + b² to find 84².
- 38.Find the value of x² − y² when x = 5 and y = 3.
- 39.If a − b = 9 and ab = 22, what is a² + b²?
- 40.Use a² − b² = (a + b)(a − b) to find 31² − 23².
Answer key
- 128
- 4896
- 8281
- 2301
- 2916
- 2759
- 9951
- 625
- 144
- 1
- 7225
- 7921
- 25
- 6241
- 58
- 2496
- 45
- 225
- 841
- 3136
- 400
- 399
- 1089
- 41
- 8051
- 945
- 440
- 2304
- 7225
- 6375
- 9801
- 3591
- 8091
- 361
- 7
- 3481
- 7056
- 16
- 125
- 432
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