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 = 4 and y = 2.
- 2.Find the value of x² + 2xy + y² when x = 14 and y = 3.
- 3.Use a² − b² = (a + b)(a − b) to find 63² − 38².
- 4.Use a² − b² = (a + b)(a − b) to find 51² − 48².
- 5.Use (a − b)² = a² − 2ab + b² to find 28².
- 6.Use (a − b)² = a² − 2ab + b² to find 43².
- 7.Use (a + b)² = a² + 2ab + b² to find 27².
- 8.Find the value of x² − y² when x = 6 and y = 2.
- 9.Use a² − b² = (a + b)(a − b) to find 79² − 41².
- 10.Use (a + b)² = a² + 2ab + b² to find 65².
- 11.Use (a − b)² = a² − 2ab + b² to find 77².
- 12.Use a² − b² = (a + b)(a − b) to find 66² − 56².
- 13.Use (a + b)² = a² + 2ab + b² to find 103².
- 14.Use (a + b)² = a² + 2ab + b² to find 47².
- 15.If a + b = 16 and ab = 55, what is a² + b²?
- 16.Use a² − b² = (a + b)(a − b) to find 65² − 15².
- 17.Find the value of x² − y² when x = 8 and y = 5.
- 18.Find the value of x² − 2xy + y² when x = 14 and y = 7.
- 19.If a − b = 1 and ab = 90, what is a² + b²?
- 20.Use (a − b)² = a² − 2ab + b² to find 32².
- 21.Use (a − b)² = a² − 2ab + b² to find 36².
- 22.Use (a + b)² = a² + 2ab + b² to find 49².
- 23.Use (a + b)² = a² + 2ab + b² to find 14².
- 24.Use (a + b)(a − b) = a² − b² to find 56 × 44.
- 25.Use (a + b)(a − b) = a² − b² to find 65 × 55.
- 26.Find the value of x² + 2xy + y² when x = 6 and y = 2.
- 27.Use (a + b)² = a² + 2ab + b² to find 79².
- 28.Use (a − b)² = a² − 2ab + b² to find 73².
- 29.Use (a + b)(a − b) = a² − b² to find 36 × 24.
- 30.Use (a + b)(a − b) = a² − b² to find 96 × 84.
- 31.Use (a + b)(a − b) = a² − b² to find 106 × 94.
- 32.Use (a + b)(a − b) = a² − b² to find 94 × 86.
- 33.Use (a + b)² = a² + 2ab + b² to find 37².
- 34.If a + b = 19 and ab = 90, what is a² + b²?
- 35.If a + b = 9 and ab = 14, what is a² + b²?
- 36.Use (a + b)(a − b) = a² − b² to find 29 × 11.
- 37.If a + b = 12 and ab = 27, what is a² + b²?
- 38.Use (a + b)² = a² + 2ab + b² to find 89².
- 39.Use (a − b)² = a² − 2ab + b² to find 46².
- 40.Find the value of x² − y² when x = 10 and y = 4.
Answer key
- 36
- 289
- 2525
- 297
- 784
- 1849
- 729
- 32
- 4560
- 4225
- 5929
- 1220
- 10609
- 2209
- 146
- 4000
- 39
- 49
- 181
- 1024
- 1296
- 2401
- 196
- 2464
- 3575
- 64
- 6241
- 5329
- 864
- 8064
- 9964
- 8084
- 1369
- 181
- 53
- 319
- 90
- 7921
- 2116
- 84
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