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 + 2xy + y² when x = 9 and y = 2.
- 2.Use (a + b)² = a² + 2ab + b² to find 31².
- 3.Use (a − b)² = a² − 2ab + b² to find 96².
- 4.Use (a − b)² = a² − 2ab + b² to find 57².
- 5.Find the value of x² + 2xy + y² when x = 11 and y = 3.
- 6.If a + b = 3 and ab = 2, what is a² + b²?
- 7.Use (a + b)² = a² + 2ab + b² to find 37².
- 8.If a − b = 2 and ab = 99, what is a² + b²?
- 9.If a + b = 5 and ab = 4, what is a² + b²?
- 10.Use (a + b)² = a² + 2ab + b² to find 62².
- 11.Use (a − b)² = a² − 2ab + b² to find 29².
- 12.Use (a + b)² = a² + 2ab + b² to find 12².
- 13.Use (a + b)(a − b) = a² − b² to find 56 × 44.
- 14.Use a² − b² = (a + b)(a − b) to find 97² − 63².
- 15.Use (a + b)(a − b) = a² − b² to find 53 × 47.
- 16.Use (a + b)(a − b) = a² − b² to find 52 × 48.
- 17.Use a² − b² = (a + b)(a − b) to find 21² − 9².
- 18.Use (a − b)² = a² − 2ab + b² to find 15².
- 19.Use (a − b)² = a² − 2ab + b² to find 36².
- 20.Find the value of x² + 2xy + y² when x = 4 and y = 1.
- 21.Find the value of x² + 2xy + y² when x = 8 and y = 2.
- 22.Find the value of x² + 2xy + y² when x = 11 and y = 5.
- 23.Use (a + b)² = a² + 2ab + b² to find 63².
- 24.If a + b = 5 and ab = 6, what is a² + b²?
- 25.Find the value of x² − 2xy + y² when x = 5 and y = 4.
- 26.Find the value of x² − 2xy + y² when x = 4 and y = 3.
- 27.Use (a + b)(a − b) = a² − b² to find 31 × 29.
- 28.Use a² − b² = (a + b)(a − b) to find 21² − 5².
- 29.Find the value of x² + 2xy + y² when x = 4 and y = 2.
- 30.Use (a + b)² = a² + 2ab + b² to find 92².
- 31.Use a² − b² = (a + b)(a − b) to find 90² − 16².
- 32.Use a² − b² = (a + b)(a − b) to find 23² − 11².
- 33.Use (a − b)² = a² − 2ab + b² to find 87².
- 34.Use a² − b² = (a + b)(a − b) to find 63² − 5².
- 35.Use (a − b)² = a² − 2ab + b² to find 79².
- 36.Use (a + b)² = a² + 2ab + b² to find 26².
- 37.Find the value of x² + 2xy + y² when x = 10 and y = 7.
- 38.Use a² − b² = (a + b)(a − b) to find 37² − 5².
- 39.Use (a + b)(a − b) = a² − b² to find 72 × 68.
- 40.Use (a − b)² = a² − 2ab + b² to find 31².
Answer key
- 121
- 961
- 9216
- 3249
- 196
- 5
- 1369
- 202
- 17
- 3844
- 841
- 144
- 2464
- 5440
- 2491
- 2496
- 360
- 225
- 1296
- 25
- 100
- 256
- 3969
- 13
- 1
- 1
- 899
- 416
- 36
- 8464
- 7844
- 408
- 7569
- 3944
- 6241
- 676
- 289
- 1344
- 4896
- 961
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