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 46².
- 2.Use (a − b)² = a² − 2ab + b² to find 23².
- 3.Find the value of x² − y² when x = 9 and y = 1.
- 4.If a + b = 3 and ab = 2, what is a² + b²?
- 5.Use (a + b)² = a² + 2ab + b² to find 62².
- 6.Use (a + b)(a − b) = a² − b² to find 32 × 28.
- 7.Use a² − b² = (a + b)(a − b) to find 68² − 53².
- 8.Use (a − b)² = a² − 2ab + b² to find 35².
- 9.Use (a + b)² = a² + 2ab + b² to find 61².
- 10.If a − b = 4 and ab = 5, what is a² + b²?
- 11.Use (a + b)² = a² + 2ab + b² to find 29².
- 12.Use (a + b)² = a² + 2ab + b² to find 11².
- 13.Find the value of x² + 2xy + y² when x = 9 and y = 8.
- 14.Use (a − b)² = a² − 2ab + b² to find 95².
- 15.Find the value of x² + 2xy + y² when x = 5 and y = 4.
- 16.Use (a + b)(a − b) = a² − b² to find 25 × 15.
- 17.Use (a + b)(a − b) = a² − b² to find 98 × 82.
- 18.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 19.Find the value of x² − y² when x = 3 and y = 1.
- 20.Use (a + b)(a − b) = a² − b² to find 68 × 52.
- 21.Use (a − b)² = a² − 2ab + b² to find 92².
- 22.Use (a − b)² = a² − 2ab + b² to find 54².
- 23.If a − b = 2 and ab = 48, what is a² + b²?
- 24.Use a² − b² = (a + b)(a − b) to find 33² − 29².
- 25.Use (a + b)(a − b) = a² − b² to find 86 × 74.
- 26.Find the value of x² + 2xy + y² when x = 3 and y = 1.
- 27.If a − b = 6 and ab = 55, what is a² + b²?
- 28.If a + b = 14 and ab = 48, what is a² + b²?
- 29.Use (a + b)² = a² + 2ab + b² to find 64².
- 30.Use (a + b)² = a² + 2ab + b² to find 77².
- 31.Use (a + b)² = a² + 2ab + b² to find 87².
- 32.Use (a + b)² = a² + 2ab + b² to find 34².
- 33.Find the value of x² − y² when x = 15 and y = 5.
- 34.Use a² − b² = (a + b)(a − b) to find 30² − 3².
- 35.Use (a + b)(a − b) = a² − b² to find 71 × 69.
- 36.Find the value of x² − y² when x = 7 and y = 4.
- 37.Use (a + b)(a − b) = a² − b² to find 59 × 41.
- 38.Use a² − b² = (a + b)(a − b) to find 51² − 19².
- 39.Find the value of x² + 2xy + y² when x = 13 and y = 4.
- 40.Use a² − b² = (a + b)(a − b) to find 65² − 21².
Answer key
- 2116
- 529
- 80
- 5
- 3844
- 896
- 1815
- 1225
- 3721
- 26
- 841
- 121
- 289
- 9025
- 81
- 375
- 8036
- 1591
- 8
- 3536
- 8464
- 2916
- 100
- 248
- 6364
- 16
- 146
- 100
- 4096
- 5929
- 7569
- 1156
- 200
- 891
- 4899
- 33
- 2419
- 2240
- 289
- 3784
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