Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 365 · 40 sums

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.

1. 1.Use a² − b² = (a + b)(a − b) to find 79² − 68².
2. 2.Find the value of x² − y² when x = 7 and y = 1.
3. 3.Use (a − b)² = a² − 2ab + b² to find 46².
4. 4.Use (a + b)(a − b) = a² − b² to find 22 × 18.
5. 5.Use a² − b² = (a + b)(a − b) to find 75² − 13².
6. 6.Find the value of x² + 2xy + y² when x = 10 and y = 3.
7. 7.Use (a + b)² = a² + 2ab + b² to find 84².
8. 8.Use (a − b)² = a² − 2ab + b² to find 41².
9. 9.Use (a − b)² = a² − 2ab + b² to find 11².
10. 10.Use (a − b)² = a² − 2ab + b² to find 38².
11. 11.If a + b = 16 and ab = 48, what is a² + b²?
12. 12.Use a² − b² = (a + b)(a − b) to find 44² − 17².
13. 13.Use (a − b)² = a² − 2ab + b² to find 79².
14. 14.Use (a + b)² = a² + 2ab + b² to find 25².
15. 15.If a + b = 4 and ab = 3, what is a² + b²?
16. 16.Use a² − b² = (a + b)(a − b) to find 48² − 24².
17. 17.Find the value of x² + 2xy + y² when x = 14 and y = 12.
18. 18.Find the value of x² − y² when x = 9 and y = 4.
19. 19.Use (a − b)² = a² − 2ab + b² to find 21².
20. 20.Use (a + b)² = a² + 2ab + b² to find 27².
21. 21.If a + b = 22 and ab = 120, what is a² + b²?
22. 22.Use (a + b)² = a² + 2ab + b² to find 56².
23. 23.If a + b = 11 and ab = 10, what is a² + b²?
24. 24.Use (a + b)(a − b) = a² − b² to find 64 × 56.
25. 25.Use (a + b)(a − b) = a² − b² to find 55 × 45.
26. 26.Use (a + b)(a − b) = a² − b² to find 25 × 15.
27. 27.Use (a + b)² = a² + 2ab + b² to find 75².
28. 28.Use (a + b)² = a² + 2ab + b² to find 88².
29. 29.Use (a + b)(a − b) = a² − b² to find 68 × 52.
30. 30.Use (a − b)² = a² − 2ab + b² to find 96².
31. 31.Find the value of x² − y² when x = 3 and y = 2.
32. 32.Use (a + b)² = a² + 2ab + b² to find 96².
33. 33.If a − b = 2 and ab = 63, what is a² + b²?
34. 34.Use a² − b² = (a + b)(a − b) to find 78² − 38².
35. 35.Use (a − b)² = a² − 2ab + b² to find 23².
36. 36.Use (a + b)² = a² + 2ab + b² to find 14².
37. 37.Use (a − b)² = a² − 2ab + b² to find 44².
38. 38.Use (a + b)(a − b) = a² − b² to find 61 × 59.
39. 39.If a − b = 6 and ab = 55, what is a² + b²?
40. 40.Use (a + b)² = a² + 2ab + b² to find 91².

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