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 − y² when x = 4 and y = 2.
- 2.Use (a − b)² = a² − 2ab + b² to find 11².
- 3.Find the value of x² + 2xy + y² when x = 3 and y = 2.
- 4.Use a² − b² = (a + b)(a − b) to find 76² − 19².
- 5.Use (a − b)² = a² − 2ab + b² to find 57².
- 6.Find the value of x² + 2xy + y² when x = 6 and y = 5.
- 7.Use (a + b)(a − b) = a² − b² to find 24 × 16.
- 8.Find the value of x² − y² when x = 4 and y = 3.
- 9.Find the value of x² − y² when x = 10 and y = 7.
- 10.Use a² − b² = (a + b)(a − b) to find 75² − 54².
- 11.Use (a + b)² = a² + 2ab + b² to find 52².
- 12.Use (a + b)² = a² + 2ab + b² to find 48².
- 13.Use (a + b)² = a² + 2ab + b² to find 36².
- 14.Find the value of x² + 2xy + y² when x = 13 and y = 3.
- 15.Use (a + b)² = a² + 2ab + b² to find 41².
- 16.Use (a + b)² = a² + 2ab + b² to find 31².
- 17.Use (a − b)² = a² − 2ab + b² to find 68².
- 18.Use (a − b)² = a² − 2ab + b² to find 18².
- 19.Use (a + b)(a − b) = a² − b² to find 23 × 17.
- 20.Use (a + b)² = a² + 2ab + b² to find 13².
- 21.Use (a + b)(a − b) = a² − b² to find 93 × 87.
- 22.Use (a + b)(a − b) = a² − b² to find 53 × 47.
- 23.Use (a − b)² = a² − 2ab + b² to find 13².
- 24.If a − b = 2 and ab = 3, what is a² + b²?
- 25.Use (a − b)² = a² − 2ab + b² to find 88².
- 26.Use (a − b)² = a² − 2ab + b² to find 39².
- 27.Use (a + b)² = a² + 2ab + b² to find 78².
- 28.If a − b = 8 and ab = 48, what is a² + b²?
- 29.Use (a + b)(a − b) = a² − b² to find 97 × 83.
- 30.If a + b = 11 and ab = 10, what is a² + b²?
- 31.Use a² − b² = (a + b)(a − b) to find 54² − 1².
- 32.Use (a − b)² = a² − 2ab + b² to find 77².
- 33.Use a² − b² = (a + b)(a − b) to find 83² − 29².
- 34.If a + b = 8 and ab = 7, what is a² + b²?
- 35.Use (a + b)(a − b) = a² − b² to find 108 × 92.
- 36.Use (a + b)(a − b) = a² − b² to find 91 × 89.
- 37.If a − b = 2 and ab = 8, what is a² + b²?
- 38.Use (a + b)(a − b) = a² − b² to find 62 × 58.
- 39.Use (a − b)² = a² − 2ab + b² to find 66².
- 40.Use (a + b)² = a² + 2ab + b² to find 96².
Answer key
- 12
- 121
- 25
- 5415
- 3249
- 121
- 384
- 7
- 51
- 2709
- 2704
- 2304
- 1296
- 256
- 1681
- 961
- 4624
- 324
- 391
- 169
- 8091
- 2491
- 169
- 10
- 7744
- 1521
- 6084
- 160
- 8051
- 101
- 2915
- 5929
- 6048
- 50
- 9936
- 8099
- 20
- 3596
- 4356
- 9216
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