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 71².
- 2.Find the value of x² − y² when x = 8 and y = 2.
- 3.If a − b = 1 and ab = 132, what is a² + b²?
- 4.Use a² − b² = (a + b)(a − b) to find 31² − 21².
- 5.If a + b = 3 and ab = 2, what is a² + b²?
- 6.Use (a + b)(a − b) = a² − b² to find 88 × 72.
- 7.Use (a + b)² = a² + 2ab + b² to find 23².
- 8.If a − b = 2 and ab = 8, what is a² + b²?
- 9.If a + b = 9 and ab = 14, what is a² + b²?
- 10.Use (a + b)² = a² + 2ab + b² to find 27².
- 11.Use (a + b)(a − b) = a² − b² to find 23 × 17.
- 12.Find the value of x² + 2xy + y² when x = 11 and y = 1.
- 13.Find the value of x² + 2xy + y² when x = 14 and y = 7.
- 14.Use (a + b)² = a² + 2ab + b² to find 25².
- 15.Find the value of x² − y² when x = 11 and y = 8.
- 16.If a + b = 13 and ab = 22, what is a² + b²?
- 17.If a + b = 5 and ab = 6, what is a² + b²?
- 18.If a + b = 13 and ab = 12, what is a² + b²?
- 19.Use (a − b)² = a² − 2ab + b² to find 95².
- 20.Use (a + b)(a − b) = a² − b² to find 41 × 39.
- 21.Find the value of x² − y² when x = 10 and y = 3.
- 22.If a + b = 12 and ab = 11, what is a² + b²?
- 23.Use (a + b)(a − b) = a² − b² to find 43 × 37.
- 24.Use (a + b)(a − b) = a² − b² to find 65 × 55.
- 25.Use (a + b)(a − b) = a² − b² to find 29 × 11.
- 26.Use a² − b² = (a + b)(a − b) to find 40² − 1².
- 27.Use (a + b)² = a² + 2ab + b² to find 34².
- 28.Find the value of x² − 2xy + y² when x = 11 and y = 6.
- 29.Use (a − b)² = a² − 2ab + b² to find 32².
- 30.Use (a + b)² = a² + 2ab + b² to find 55².
- 31.Find the value of x² − 2xy + y² when x = 6 and y = 5.
- 32.Use (a + b)² = a² + 2ab + b² to find 84².
- 33.Use (a + b)(a − b) = a² − b² to find 54 × 46.
- 34.Use a² − b² = (a + b)(a − b) to find 58² − 56².
- 35.Use (a − b)² = a² − 2ab + b² to find 87².
- 36.If a − b = 1 and ab = 2, what is a² + b²?
- 37.Use (a − b)² = a² − 2ab + b² to find 88².
- 38.Find the value of x² − 2xy + y² when x = 14 and y = 9.
- 39.Use (a − b)² = a² − 2ab + b² to find 84².
- 40.If a + b = 16 and ab = 60, what is a² + b²?
Answer key
- 5041
- 60
- 265
- 520
- 5
- 6336
- 529
- 20
- 53
- 729
- 391
- 144
- 441
- 625
- 57
- 125
- 13
- 145
- 9025
- 1599
- 91
- 122
- 1591
- 3575
- 319
- 1599
- 1156
- 25
- 1024
- 3025
- 1
- 7056
- 2484
- 228
- 7569
- 5
- 7744
- 25
- 7056
- 136
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