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 16².
- 2.If a + b = 4 and ab = 3, what is a² + b²?
- 3.Use a² − b² = (a + b)(a − b) to find 61² − 35².
- 4.If a + b = 9 and ab = 18, what is a² + b²?
- 5.Find the value of x² − 2xy + y² when x = 15 and y = 8.
- 6.Use a² − b² = (a + b)(a − b) to find 88² − 27².
- 7.Use (a + b)² = a² + 2ab + b² to find 23².
- 8.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 9.Use (a + b)(a − b) = a² − b² to find 23 × 17.
- 10.If a − b = 1 and ab = 30, what is a² + b²?
- 11.Find the value of x² − y² when x = 8 and y = 1.
- 12.Find the value of x² − y² when x = 13 and y = 7.
- 13.Use (a + b)² = a² + 2ab + b² to find 73².
- 14.Use (a + b)² = a² + 2ab + b² to find 28².
- 15.If a + b = 17 and ab = 60, what is a² + b²?
- 16.Use a² − b² = (a + b)(a − b) to find 72² − 42².
- 17.Use (a + b)² = a² + 2ab + b² to find 98².
- 18.Use (a + b)(a − b) = a² − b² to find 34 × 26.
- 19.Use (a + b)² = a² + 2ab + b² to find 31².
- 20.Find the value of x² − y² when x = 4 and y = 2.
- 21.Use (a − b)² = a² − 2ab + b² to find 84².
- 22.If a − b = 6 and ab = 55, what is a² + b²?
- 23.Use a² − b² = (a + b)(a − b) to find 26² − 6².
- 24.If a + b = 14 and ab = 45, what is a² + b²?
- 25.Find the value of x² + 2xy + y² when x = 15 and y = 1.
- 26.If a − b = 2 and ab = 15, what is a² + b²?
- 27.If a + b = 12 and ab = 32, what is a² + b²?
- 28.Use (a + b)² = a² + 2ab + b² to find 13².
- 29.Use (a − b)² = a² − 2ab + b² to find 37².
- 30.Use a² − b² = (a + b)(a − b) to find 74² − 34².
- 31.Use (a + b)² = a² + 2ab + b² to find 37².
- 32.Find the value of x² + 2xy + y² when x = 12 and y = 1.
- 33.If a − b = 1 and ab = 2, what is a² + b²?
- 34.Use (a − b)² = a² − 2ab + b² to find 77².
- 35.Use (a − b)² = a² − 2ab + b² to find 17².
- 36.Find the value of x² + 2xy + y² when x = 4 and y = 1.
- 37.Find the value of x² − y² when x = 13 and y = 5.
- 38.Use a² − b² = (a + b)(a − b) to find 37² − 31².
- 39.Use (a − b)² = a² − 2ab + b² to find 64².
- 40.Use (a + b)² = a² + 2ab + b² to find 46².
Answer key
- 256
- 10
- 2496
- 45
- 49
- 7015
- 529
- 399
- 391
- 61
- 63
- 120
- 5329
- 784
- 169
- 3420
- 9604
- 884
- 961
- 12
- 7056
- 146
- 640
- 106
- 256
- 34
- 80
- 169
- 1369
- 4320
- 1369
- 169
- 5
- 5929
- 289
- 25
- 144
- 408
- 4096
- 2116
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