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 = 2.
- 2.Use (a + b)² = a² + 2ab + b² to find 66².
- 3.Use a² − b² = (a + b)(a − b) to find 21² − 11².
- 4.Use (a + b)(a − b) = a² − b² to find 51 × 49.
- 5.If a + b = 3 and ab = 2, what is a² + b²?
- 6.Use (a + b)² = a² + 2ab + b² to find 105².
- 7.If a − b = 6 and ab = 55, what is a² + b²?
- 8.Find the value of x² + 2xy + y² when x = 7 and y = 3.
- 9.Find the value of x² + 2xy + y² when x = 3 and y = 1.
- 10.Use a² − b² = (a + b)(a − b) to find 43² − 12².
- 11.If a − b = 1 and ab = 30, what is a² + b²?
- 12.Find the value of x² + 2xy + y² when x = 14 and y = 3.
- 13.If a + b = 6 and ab = 8, what is a² + b²?
- 14.Use a² − b² = (a + b)(a − b) to find 77² − 14².
- 15.Use a² − b² = (a + b)(a − b) to find 90² − 80².
- 16.Use (a − b)² = a² − 2ab + b² to find 47².
- 17.Use a² − b² = (a + b)(a − b) to find 43² − 23².
- 18.Use (a + b)(a − b) = a² − b² to find 53 × 47.
- 19.Use (a − b)² = a² − 2ab + b² to find 55².
- 20.Use (a − b)² = a² − 2ab + b² to find 91².
- 21.If a − b = 2 and ab = 3, what is a² + b²?
- 22.Find the value of x² − y² when x = 11 and y = 3.
- 23.Use (a + b)(a − b) = a² − b² to find 105 × 95.
- 24.Use (a + b)² = a² + 2ab + b² to find 58².
- 25.Use (a + b)² = a² + 2ab + b² to find 37².
- 26.Find the value of x² − 2xy + y² when x = 7 and y = 5.
- 27.Find the value of x² + 2xy + y² when x = 6 and y = 4.
- 28.Use (a + b)² = a² + 2ab + b² to find 11².
- 29.Use (a + b)² = a² + 2ab + b² to find 44².
- 30.If a − b = 2 and ab = 15, what is a² + b²?
- 31.Use (a − b)² = a² − 2ab + b² to find 52².
- 32.If a + b = 12 and ab = 32, what is a² + b²?
- 33.Find the value of x² + 2xy + y² when x = 7 and y = 6.
- 34.Use (a − b)² = a² − 2ab + b² to find 24².
- 35.Use (a + b)(a − b) = a² − b² to find 49 × 31.
- 36.Use (a + b)(a − b) = a² − b² to find 47 × 33.
- 37.Use (a + b)² = a² + 2ab + b² to find 72².
- 38.Use (a − b)² = a² − 2ab + b² to find 39².
- 39.Use a² − b² = (a + b)(a − b) to find 42² − 6².
- 40.Use (a + b)² = a² + 2ab + b² to find 97².
Answer key
- 140
- 4356
- 320
- 2499
- 5
- 11025
- 146
- 100
- 16
- 1705
- 61
- 289
- 20
- 5733
- 1700
- 2209
- 1320
- 2491
- 3025
- 8281
- 10
- 112
- 9975
- 3364
- 1369
- 4
- 100
- 121
- 1936
- 34
- 2704
- 80
- 169
- 576
- 1519
- 1551
- 5184
- 1521
- 1728
- 9409
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