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)(a − b) = a² − b² to find 103 × 97.
- 2.Use (a − b)² = a² − 2ab + b² to find 29².
- 3.Use (a + b)(a − b) = a² − b² to find 33 × 27.
- 4.Use (a + b)² = a² + 2ab + b² to find 45².
- 5.Use a² − b² = (a + b)(a − b) to find 83² − 11².
- 6.Use a² − b² = (a + b)(a − b) to find 62² − 60².
- 7.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 8.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 9.Use (a + b)² = a² + 2ab + b² to find 35².
- 10.Use (a + b)² = a² + 2ab + b² to find 21².
- 11.If a + b = 19 and ab = 84, what is a² + b²?
- 12.Use (a + b)² = a² + 2ab + b² to find 59².
- 13.If a + b = 7 and ab = 12, what is a² + b²?
- 14.If a + b = 6 and ab = 8, what is a² + b²?
- 15.If a − b = 3 and ab = 28, what is a² + b²?
- 16.Use (a − b)² = a² − 2ab + b² to find 67².
- 17.Use (a + b)(a − b) = a² − b² to find 21 × 19.
- 18.Use (a + b)(a − b) = a² − b² to find 32 × 28.
- 19.Use (a + b)(a − b) = a² − b² to find 64 × 56.
- 20.Use a² − b² = (a + b)(a − b) to find 86² − 39².
- 21.Find the value of x² − y² when x = 6 and y = 1.
- 22.Find the value of x² + 2xy + y² when x = 5 and y = 2.
- 23.Find the value of x² − 2xy + y² when x = 15 and y = 9.
- 24.If a − b = 2 and ab = 63, what is a² + b²?
- 25.Find the value of x² + 2xy + y² when x = 12 and y = 8.
- 26.Use (a + b)(a − b) = a² − b² to find 61 × 59.
- 27.Use a² − b² = (a + b)(a − b) to find 91² − 49².
- 28.Use (a + b)² = a² + 2ab + b² to find 34².
- 29.If a − b = 4 and ab = 5, what is a² + b²?
- 30.Use a² − b² = (a + b)(a − b) to find 43² − 11².
- 31.Use (a + b)(a − b) = a² − b² to find 29 × 11.
- 32.If a + b = 3 and ab = 2, what is a² + b²?
- 33.Use (a + b)² = a² + 2ab + b² to find 67².
- 34.Use (a + b)(a − b) = a² − b² to find 35 × 25.
- 35.Use (a + b)(a − b) = a² − b² to find 73 × 67.
- 36.Use (a + b)² = a² + 2ab + b² to find 95².
- 37.Find the value of x² + 2xy + y² when x = 11 and y = 1.
- 38.Use a² − b² = (a + b)(a − b) to find 55² − 1².
- 39.Use (a − b)² = a² − 2ab + b² to find 17².
- 40.Use (a − b)² = a² − 2ab + b² to find 28².
Answer key
- 9991
- 841
- 891
- 2025
- 6768
- 244
- 2484
- 1591
- 1225
- 441
- 193
- 3481
- 25
- 20
- 65
- 4489
- 399
- 896
- 3584
- 5875
- 35
- 49
- 36
- 130
- 400
- 3599
- 5880
- 1156
- 26
- 1728
- 319
- 5
- 4489
- 875
- 4891
- 9025
- 144
- 3024
- 289
- 784
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