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.If a + b = 5 and ab = 6, what is a² + b²?
- 2.If a + b = 22 and ab = 120, what is a² + b²?
- 3.Use (a − b)² = a² − 2ab + b² to find 32².
- 4.If a + b = 15 and ab = 36, what is a² + b²?
- 5.Find the value of x² − 2xy + y² when x = 3 and y = 2.
- 6.Use (a − b)² = a² − 2ab + b² to find 68².
- 7.If a − b = 10 and ab = 11, what is a² + b²?
- 8.Use (a − b)² = a² − 2ab + b² to find 27².
- 9.Use a² − b² = (a + b)(a − b) to find 98² − 3².
- 10.Use (a − b)² = a² − 2ab + b² to find 56².
- 11.Use (a − b)² = a² − 2ab + b² to find 62².
- 12.If a + b = 10 and ab = 16, what is a² + b²?
- 13.If a + b = 15 and ab = 50, what is a² + b²?
- 14.Find the value of x² − y² when x = 11 and y = 1.
- 15.Use a² − b² = (a + b)(a − b) to find 47² − 12².
- 16.Use (a + b)² = a² + 2ab + b² to find 21².
- 17.Find the value of x² − y² when x = 6 and y = 1.
- 18.Use (a + b)² = a² + 2ab + b² to find 39².
- 19.Use (a + b)² = a² + 2ab + b² to find 13².
- 20.If a + b = 18 and ab = 72, what is a² + b²?
- 21.If a + b = 8 and ab = 7, what is a² + b²?
- 22.Use (a − b)² = a² − 2ab + b² to find 21².
- 23.Use (a + b)² = a² + 2ab + b² to find 61².
- 24.Find the value of x² − y² when x = 11 and y = 10.
- 25.Use (a − b)² = a² − 2ab + b² to find 83².
- 26.Use a² − b² = (a + b)(a − b) to find 71² − 52².
- 27.If a + b = 8 and ab = 12, what is a² + b²?
- 28.Use a² − b² = (a + b)(a − b) to find 53² − 33².
- 29.Find the value of x² − y² when x = 11 and y = 6.
- 30.Use (a − b)² = a² − 2ab + b² to find 14².
- 31.If a − b = 2 and ab = 3, what is a² + b²?
- 32.Use (a + b)(a − b) = a² − b² to find 63 × 57.
- 33.Use (a + b)(a − b) = a² − b² to find 74 × 66.
- 34.If a + b = 20 and ab = 96, what is a² + b²?
- 35.If a − b = 3 and ab = 88, what is a² + b²?
- 36.Find the value of x² − y² when x = 10 and y = 6.
- 37.Find the value of x² − 2xy + y² when x = 9 and y = 3.
- 38.Use (a + b)² = a² + 2ab + b² to find 55².
- 39.Use (a + b)(a − b) = a² − b² to find 94 × 86.
- 40.If a + b = 10 and ab = 9, what is a² + b²?
Answer key
- 13
- 244
- 1024
- 153
- 1
- 4624
- 122
- 729
- 9595
- 3136
- 3844
- 68
- 125
- 120
- 2065
- 441
- 35
- 1521
- 169
- 180
- 50
- 441
- 3721
- 21
- 6889
- 2337
- 40
- 1720
- 85
- 196
- 10
- 3591
- 4884
- 208
- 185
- 64
- 36
- 3025
- 8084
- 82
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