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.If a + b = 7 and ab = 10, what is a² + b²?
- 2.Use (a − b)² = a² − 2ab + b² to find 59².
- 3.If a + b = 9 and ab = 18, what is a² + b²?
- 4.Use (a + b)(a − b) = a² − b² to find 34 × 26.
- 5.If a − b = 1 and ab = 2, what is a² + b²?
- 6.Use (a + b)² = a² + 2ab + b² to find 62².
- 7.Find the value of x² − 2xy + y² when x = 6 and y = 3.
- 8.Use (a + b)(a − b) = a² − b² to find 84 × 76.
- 9.Find the value of x² − y² when x = 5 and y = 2.
- 10.If a + b = 17 and ab = 72, what is a² + b²?
- 11.Find the value of x² − y² when x = 6 and y = 3.
- 12.Find the value of x² + 2xy + y² when x = 3 and y = 1.
- 13.Use a² − b² = (a + b)(a − b) to find 42² − 17².
- 14.Use (a − b)² = a² − 2ab + b² to find 77².
- 15.Use (a − b)² = a² − 2ab + b² to find 85².
- 16.If a + b = 13 and ab = 36, what is a² + b²?
- 17.Use (a + b)² = a² + 2ab + b² to find 49².
- 18.Use (a − b)² = a² − 2ab + b² to find 46².
- 19.If a − b = 1 and ab = 30, what is a² + b²?
- 20.Use (a − b)² = a² − 2ab + b² to find 11².
- 21.Use (a + b)² = a² + 2ab + b² to find 84².
- 22.Use (a + b)² = a² + 2ab + b² to find 77².
- 23.Use (a − b)² = a² − 2ab + b² to find 14².
- 24.Use a² − b² = (a + b)(a − b) to find 52² − 37².
- 25.Use (a − b)² = a² − 2ab + b² to find 21².
- 26.If a − b = 6 and ab = 55, what is a² + b²?
- 27.Use a² − b² = (a + b)(a − b) to find 29² − 12².
- 28.Find the value of x² + 2xy + y² when x = 11 and y = 6.
- 29.Use (a + b)² = a² + 2ab + b² to find 48².
- 30.Use (a + b)(a − b) = a² − b² to find 101 × 99.
- 31.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 32.Use (a − b)² = a² − 2ab + b² to find 28².
- 33.Use a² − b² = (a + b)(a − b) to find 23² − 2².
- 34.If a − b = 3 and ab = 28, what is a² + b²?
- 35.Use (a + b)(a − b) = a² − b² to find 66 × 54.
- 36.Use a² − b² = (a + b)(a − b) to find 29² − 27².
- 37.Use a² − b² = (a + b)(a − b) to find 47² − 33².
- 38.Find the value of x² − 2xy + y² when x = 11 and y = 9.
- 39.Use a² − b² = (a + b)(a − b) to find 89² − 74².
- 40.Use (a + b)² = a² + 2ab + b² to find 13².
Answer key
- 29
- 3481
- 45
- 884
- 5
- 3844
- 9
- 6384
- 21
- 145
- 27
- 16
- 1475
- 5929
- 7225
- 97
- 2401
- 2116
- 61
- 121
- 7056
- 5929
- 196
- 1335
- 441
- 146
- 697
- 289
- 2304
- 9999
- 875
- 784
- 525
- 65
- 3564
- 112
- 1120
- 4
- 2445
- 169
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