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 24 × 16.
- 2.Use a² − b² = (a + b)(a − b) to find 47² − 18².
- 3.If a − b = 6 and ab = 72, what is a² + b²?
- 4.Use (a − b)² = a² − 2ab + b² to find 63².
- 5.Use a² − b² = (a + b)(a − b) to find 93² − 41².
- 6.Use a² − b² = (a + b)(a − b) to find 55² − 28².
- 7.Use (a + b)² = a² + 2ab + b² to find 57².
- 8.Use a² − b² = (a + b)(a − b) to find 75² − 31².
- 9.Use (a − b)² = a² − 2ab + b² to find 31².
- 10.If a + b = 5 and ab = 6, what is a² + b²?
- 11.Find the value of x² − 2xy + y² when x = 15 and y = 11.
- 12.Use (a − b)² = a² − 2ab + b² to find 16².
- 13.Use a² − b² = (a + b)(a − b) to find 91² − 25².
- 14.Use a² − b² = (a + b)(a − b) to find 38² − 15².
- 15.Find the value of x² − y² when x = 13 and y = 4.
- 16.Find the value of x² + 2xy + y² when x = 5 and y = 2.
- 17.Use (a + b)² = a² + 2ab + b² to find 58².
- 18.Use (a − b)² = a² − 2ab + b² to find 26².
- 19.Find the value of x² − 2xy + y² when x = 6 and y = 1.
- 20.Use (a + b)² = a² + 2ab + b² to find 17².
- 21.Use a² − b² = (a + b)(a − b) to find 35² − 7².
- 22.Use (a + b)² = a² + 2ab + b² to find 69².
- 23.Use (a − b)² = a² − 2ab + b² to find 91².
- 24.Use (a − b)² = a² − 2ab + b² to find 33².
- 25.Use (a + b)² = a² + 2ab + b² to find 23².
- 26.Use (a + b)² = a² + 2ab + b² to find 73².
- 27.If a + b = 4 and ab = 3, what is a² + b²?
- 28.Find the value of x² + 2xy + y² when x = 5 and y = 3.
- 29.Use a² − b² = (a + b)(a − b) to find 41² − 33².
- 30.Use (a + b)(a − b) = a² − b² to find 72 × 68.
- 31.If a − b = 7 and ab = 60, what is a² + b²?
- 32.Use (a − b)² = a² − 2ab + b² to find 82².
- 33.Use (a + b)(a − b) = a² − b² to find 33 × 27.
- 34.Use a² − b² = (a + b)(a − b) to find 47² − 34².
- 35.Find the value of x² + 2xy + y² when x = 9 and y = 2.
- 36.Use (a + b)² = a² + 2ab + b² to find 98².
- 37.Use a² − b² = (a + b)(a − b) to find 85² − 16².
- 38.Use (a − b)² = a² − 2ab + b² to find 62².
- 39.If a − b = 4 and ab = 5, what is a² + b²?
- 40.Use (a − b)² = a² − 2ab + b² to find 72².
Answer key
- 384
- 1885
- 180
- 3969
- 6968
- 2241
- 3249
- 4664
- 961
- 13
- 16
- 256
- 7656
- 1219
- 153
- 49
- 3364
- 676
- 25
- 289
- 1176
- 4761
- 8281
- 1089
- 529
- 5329
- 10
- 64
- 592
- 4896
- 169
- 6724
- 891
- 1053
- 121
- 9604
- 6969
- 3844
- 26
- 5184
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