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 = 7 and y = 1.
- 2.If a − b = 11 and ab = 12, what is a² + b²?
- 3.Find the value of x² − y² when x = 13 and y = 5.
- 4.Use (a − b)² = a² − 2ab + b² to find 91².
- 5.Find the value of x² + 2xy + y² when x = 6 and y = 3.
- 6.Find the value of x² − 2xy + y² when x = 8 and y = 1.
- 7.Find the value of x² − y² when x = 9 and y = 1.
- 8.Use a² − b² = (a + b)(a − b) to find 22² − 2².
- 9.Use (a + b)² = a² + 2ab + b² to find 27².
- 10.Use a² − b² = (a + b)(a − b) to find 71² − 21².
- 11.Find the value of x² − y² when x = 7 and y = 5.
- 12.Use (a − b)² = a² − 2ab + b² to find 94².
- 13.Use (a − b)² = a² − 2ab + b² to find 26².
- 14.Use (a − b)² = a² − 2ab + b² to find 86².
- 15.Use (a − b)² = a² − 2ab + b² to find 79².
- 16.Use (a − b)² = a² − 2ab + b² to find 65².
- 17.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 18.Use (a + b)(a − b) = a² − b² to find 41 × 39.
- 19.Use (a − b)² = a² − 2ab + b² to find 57².
- 20.If a − b = 9 and ab = 36, what is a² + b²?
- 21.Use a² − b² = (a + b)(a − b) to find 32² − 8².
- 22.Use a² − b² = (a + b)(a − b) to find 61² − 37².
- 23.Use (a + b)² = a² + 2ab + b² to find 94².
- 24.Use (a + b)² = a² + 2ab + b² to find 21².
- 25.Use a² − b² = (a + b)(a − b) to find 20² − 19².
- 26.Use (a + b)² = a² + 2ab + b² to find 93².
- 27.Use (a + b)(a − b) = a² − b² to find 52 × 48.
- 28.Find the value of x² + 2xy + y² when x = 8 and y = 2.
- 29.Use (a + b)(a − b) = a² − b² to find 101 × 99.
- 30.Use (a + b)² = a² + 2ab + b² to find 89².
- 31.Find the value of x² + 2xy + y² when x = 6 and y = 2.
- 32.Find the value of x² + 2xy + y² when x = 11 and y = 1.
- 33.If a − b = 1 and ab = 12, what is a² + b²?
- 34.Use (a + b)² = a² + 2ab + b² to find 14².
- 35.Find the value of x² + 2xy + y² when x = 4 and y = 2.
- 36.Use (a + b)(a − b) = a² − b² to find 89 × 71.
- 37.Use (a + b)(a − b) = a² − b² to find 25 × 15.
- 38.If a − b = 1 and ab = 72, what is a² + b²?
- 39.Find the value of x² − 2xy + y² when x = 6 and y = 1.
- 40.If a + b = 4 and ab = 3, what is a² + b²?
Answer key
- 48
- 145
- 144
- 8281
- 81
- 49
- 80
- 480
- 729
- 4600
- 24
- 8836
- 676
- 7396
- 6241
- 4225
- 875
- 1599
- 3249
- 153
- 960
- 2352
- 8836
- 441
- 39
- 8649
- 2496
- 100
- 9999
- 7921
- 64
- 144
- 25
- 196
- 36
- 6319
- 375
- 145
- 25
- 10
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