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 36².
- 2.If a − b = 1 and ab = 6, what is a² + b²?
- 3.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 4.Use (a + b)² = a² + 2ab + b² to find 24².
- 5.Find the value of x² − 2xy + y² when x = 4 and y = 1.
- 6.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 7.Use (a − b)² = a² − 2ab + b² to find 57².
- 8.If a − b = 1 and ab = 110, what is a² + b²?
- 9.If a − b = 3 and ab = 18, what is a² + b²?
- 10.Use a² − b² = (a + b)(a − b) to find 72² − 20².
- 11.Find the value of x² − y² when x = 6 and y = 3.
- 12.Use (a + b)² = a² + 2ab + b² to find 18².
- 13.Use (a + b)² = a² + 2ab + b² to find 87².
- 14.If a − b = 5 and ab = 66, what is a² + b²?
- 15.Use (a + b)(a − b) = a² − b² to find 102 × 98.
- 16.Use a² − b² = (a + b)(a − b) to find 59² − 9².
- 17.Use (a + b)(a − b) = a² − b² to find 22 × 18.
- 18.Use a² − b² = (a + b)(a − b) to find 94² − 37².
- 19.Use a² − b² = (a + b)(a − b) to find 29² − 9².
- 20.Use (a + b)² = a² + 2ab + b² to find 44².
- 21.Use (a − b)² = a² − 2ab + b² to find 52².
- 22.Use (a + b)² = a² + 2ab + b² to find 67².
- 23.Use (a + b)² = a² + 2ab + b² to find 104².
- 24.Use (a + b)(a − b) = a² − b² to find 72 × 68.
- 25.If a + b = 16 and ab = 60, what is a² + b²?
- 26.If a + b = 4 and ab = 3, what is a² + b²?
- 27.Use (a − b)² = a² − 2ab + b² to find 86².
- 28.Use (a + b)² = a² + 2ab + b² to find 14².
- 29.Use (a − b)² = a² − 2ab + b² to find 47².
- 30.Find the value of x² − 2xy + y² when x = 6 and y = 4.
- 31.Find the value of x² + 2xy + y² when x = 8 and y = 5.
- 32.Use (a − b)² = a² − 2ab + b² to find 29².
- 33.Use (a − b)² = a² − 2ab + b² to find 45².
- 34.Use (a + b)(a − b) = a² − b² to find 95 × 85.
- 35.Use (a − b)² = a² − 2ab + b² to find 32².
- 36.Use a² − b² = (a + b)(a − b) to find 75² − 6².
- 37.If a − b = 1 and ab = 2, what is a² + b²?
- 38.Use (a + b)(a − b) = a² − b² to find 93 × 87.
- 39.Use (a + b)(a − b) = a² − b² to find 81 × 79.
- 40.Use a² − b² = (a + b)(a − b) to find 91² − 24².
Answer key
- 1296
- 13
- 25
- 576
- 9
- 875
- 3249
- 221
- 45
- 4784
- 27
- 324
- 7569
- 157
- 9996
- 3400
- 396
- 7467
- 760
- 1936
- 2704
- 4489
- 10816
- 4896
- 136
- 10
- 7396
- 196
- 2209
- 4
- 169
- 841
- 2025
- 8075
- 1024
- 5589
- 5
- 8091
- 6399
- 7705
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