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 a² − b² = (a + b)(a − b) to find 50² − 24².
- 2.Use (a − b)² = a² − 2ab + b² to find 59².
- 3.Use a² − b² = (a + b)(a − b) to find 59² − 36².
- 4.If a − b = 2 and ab = 48, what is a² + b²?
- 5.Use (a − b)² = a² − 2ab + b² to find 13².
- 6.Use (a + b)(a − b) = a² − b² to find 99 × 81.
- 7.Find the value of x² − y² when x = 4 and y = 2.
- 8.Use a² − b² = (a + b)(a − b) to find 60² − 10².
- 9.If a − b = 8 and ab = 9, what is a² + b²?
- 10.Use (a + b)² = a² + 2ab + b² to find 17².
- 11.Use (a − b)² = a² − 2ab + b² to find 54².
- 12.Find the value of x² − 2xy + y² when x = 14 and y = 1.
- 13.Use (a + b)² = a² + 2ab + b² to find 14².
- 14.Use (a − b)² = a² − 2ab + b² to find 49².
- 15.Use a² − b² = (a + b)(a − b) to find 22² − 18².
- 16.Find the value of x² + 2xy + y² when x = 7 and y = 2.
- 17.If a + b = 13 and ab = 12, what is a² + b²?
- 18.Use (a − b)² = a² − 2ab + b² to find 87².
- 19.Use (a + b)(a − b) = a² − b² to find 81 × 79.
- 20.If a + b = 3 and ab = 2, what is a² + b²?
- 21.Use (a + b)² = a² + 2ab + b² to find 49².
- 22.Use (a − b)² = a² − 2ab + b² to find 97².
- 23.Use (a + b)² = a² + 2ab + b² to find 86².
- 24.Find the value of x² + 2xy + y² when x = 4 and y = 2.
- 25.If a + b = 4 and ab = 3, what is a² + b²?
- 26.Use a² − b² = (a + b)(a − b) to find 89² − 52².
- 27.If a + b = 15 and ab = 54, what is a² + b²?
- 28.Use (a + b)² = a² + 2ab + b² to find 48².
- 29.Use (a − b)² = a² − 2ab + b² to find 46².
- 30.If a − b = 7 and ab = 8, what is a² + b²?
- 31.Find the value of x² − 2xy + y² when x = 14 and y = 13.
- 32.Find the value of x² − 2xy + y² when x = 7 and y = 2.
- 33.Find the value of x² − 2xy + y² when x = 9 and y = 3.
- 34.Use (a + b)(a − b) = a² − b² to find 44 × 36.
- 35.Use (a + b)² = a² + 2ab + b² to find 102².
- 36.Use (a − b)² = a² − 2ab + b² to find 85².
- 37.Use (a + b)² = a² + 2ab + b² to find 39².
- 38.Use a² − b² = (a + b)(a − b) to find 88² − 81².
- 39.Use (a + b)² = a² + 2ab + b² to find 101².
- 40.Use (a − b)² = a² − 2ab + b² to find 96².
Answer key
- 1924
- 3481
- 2185
- 100
- 169
- 8019
- 12
- 3500
- 82
- 289
- 2916
- 169
- 196
- 2401
- 160
- 81
- 145
- 7569
- 6399
- 5
- 2401
- 9409
- 7396
- 36
- 10
- 5217
- 117
- 2304
- 2116
- 65
- 1
- 25
- 36
- 1584
- 10404
- 7225
- 1521
- 1183
- 10201
- 9216
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