Class 8 Maths Worksheet: Algebraic Identities

Maths worksheets lesson 61: Algebraic identities · Set 800 · 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)(a − b) = a² − b² to find 102 × 98.
2. 2.Find the value of x² + 2xy + y² when x = 8 and y = 5.
3. 3.Use (a − b)² = a² − 2ab + b² to find 37².
4. 4.Use (a − b)² = a² − 2ab + b² to find 44².
5. 5.Use (a + b)² = a² + 2ab + b² to find 72².
6. 6.Use (a + b)² = a² + 2ab + b² to find 45².
7. 7.Find the value of x² − 2xy + y² when x = 8 and y = 1.
8. 8.Find the value of x² + 2xy + y² when x = 14 and y = 6.
9. 9.Use (a + b)(a − b) = a² − b² to find 39 × 21.
10. 10.If a + b = 10 and ab = 21, what is a² + b²?
11. 11.Use (a − b)² = a² − 2ab + b² to find 94².
12. 12.Use (a − b)² = a² − 2ab + b² to find 42².
13. 13.Use (a + b)² = a² + 2ab + b² to find 35².
14. 14.Use (a + b)(a − b) = a² − b² to find 54 × 46.
15. 15.Use (a + b)² = a² + 2ab + b² to find 11².
16. 16.Use (a + b)(a − b) = a² − b² to find 93 × 87.
17. 17.Use a² − b² = (a + b)(a − b) to find 34² − 11².
18. 18.If a − b = 3 and ab = 40, what is a² + b²?
19. 19.Find the value of x² − y² when x = 12 and y = 3.
20. 20.Use (a + b)² = a² + 2ab + b² to find 102².
21. 21.If a + b = 6 and ab = 8, what is a² + b²?
22. 22.Use a² − b² = (a + b)(a − b) to find 88² − 15².
23. 23.Use (a − b)² = a² − 2ab + b² to find 89².
24. 24.Use (a − b)² = a² − 2ab + b² to find 88².
25. 25.Use (a + b)(a − b) = a² − b² to find 108 × 92.
26. 26.Use (a − b)² = a² − 2ab + b² to find 43².
27. 27.Use (a + b)² = a² + 2ab + b² to find 101².
28. 28.Use (a − b)² = a² − 2ab + b² to find 47².
29. 29.Use (a − b)² = a² − 2ab + b² to find 21².
30. 30.Use (a − b)² = a² − 2ab + b² to find 16².
31. 31.Use (a − b)² = a² − 2ab + b² to find 68².
32. 32.Use (a + b)² = a² + 2ab + b² to find 46².
33. 33.Use (a + b)(a − b) = a² − b² to find 89 × 71.
34. 34.Use (a + b)(a − b) = a² − b² to find 76 × 64.
35. 35.Use (a + b)² = a² + 2ab + b² to find 74².
36. 36.Use (a + b)(a − b) = a² − b² to find 73 × 67.
37. 37.Use (a + b)² = a² + 2ab + b² to find 73².
38. 38.Use (a + b)² = a² + 2ab + b² to find 18².
39. 39.Use a² − b² = (a + b)(a − b) to find 91² − 19².
40. 40.Use (a + b)(a − b) = a² − b² to find 79 × 61.

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