Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 878 · 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 (a − b)² = a² − 2ab + b² to find 22².
2. 2.Use (a + b)² = a² + 2ab + b² to find 26².
3. 3.Use (a + b)(a − b) = a² − b² to find 97 × 83.
4. 4.Use (a + b)² = a² + 2ab + b² to find 53².
5. 5.Use (a + b)(a − b) = a² − b² to find 72 × 68.
6. 6.Find the value of x² + 2xy + y² when x = 13 and y = 7.
7. 7.Use (a + b)² = a² + 2ab + b² to find 33².
8. 8.Use (a − b)² = a² − 2ab + b² to find 19².
9. 9.Use (a − b)² = a² − 2ab + b² to find 62².
10. 10.If a − b = 5 and ab = 6, what is a² + b²?
11. 11.Use (a − b)² = a² − 2ab + b² to find 65².
12. 12.Use (a + b)² = a² + 2ab + b² to find 98².
13. 13.If a + b = 17 and ab = 66, what is a² + b²?
14. 14.If a + b = 8 and ab = 12, what is a² + b²?
15. 15.Use (a + b)(a − b) = a² − b² to find 89 × 71.
16. 16.Use (a − b)² = a² − 2ab + b² to find 72².
17. 17.Use (a + b)² = a² + 2ab + b² to find 15².
18. 18.Use (a + b)(a − b) = a² − b² to find 32 × 28.
19. 19.Use (a + b)² = a² + 2ab + b² to find 79².
20. 20.Use (a + b)(a − b) = a² − b² to find 47 × 33.
21. 21.Find the value of x² − y² when x = 4 and y = 3.
22. 22.Use (a − b)² = a² − 2ab + b² to find 39².
23. 23.Use (a − b)² = a² − 2ab + b² to find 81².
24. 24.Use (a + b)² = a² + 2ab + b² to find 37².
25. 25.Use (a − b)² = a² − 2ab + b² to find 15².
26. 26.Use (a + b)(a − b) = a² − b² to find 71 × 69.
27. 27.Find the value of x² + 2xy + y² when x = 5 and y = 2.
28. 28.If a − b = 1 and ab = 6, what is a² + b²?
29. 29.Use (a + b)² = a² + 2ab + b² to find 102².
30. 30.Use a² − b² = (a + b)(a − b) to find 31² − 21².
31. 31.Use (a + b)² = a² + 2ab + b² to find 107².
32. 32.Use a² − b² = (a + b)(a − b) to find 78² − 62².
33. 33.Use (a + b)(a − b) = a² − b² to find 36 × 24.
34. 34.Use (a − b)² = a² − 2ab + b² to find 14².
35. 35.Use a² − b² = (a + b)(a − b) to find 92² − 88².
36. 36.Use (a − b)² = a² − 2ab + b² to find 77².
37. 37.Use (a + b)² = a² + 2ab + b² to find 59².
38. 38.If a + b = 3 and ab = 2, what is a² + b²?
39. 39.Use (a + b)(a − b) = a² − b² to find 93 × 87.
40. 40.Use (a + b)² = a² + 2ab + b² to find 74².

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