Page:Elementary algebra (1896).djvu/30

12 We need not, however, adhere strictly to this rule, for the terms may be added or subtracted in the order we find most convenient.

This process is called collecting terms.

Find the sum of

1. $$5a, 7a, 11a, a, 23a$$.

2. $$4x, x, 3x, 7x, 9x$$.

3. $$7b, 10b, 11b, 9b, 2b$$.

4. $$6c, 8c, 2c, 15c, 19c, 100c, c$$.

5. $$-3x,-5x,-11x,-7x$$.

6. $$-5b,-6b,-11b,-18b$$.

7. $$-3y,-7y,-y,-2y,-4y$$.

8. $$-c,-2c,-50c,-13c$$.

9. $$-11b,-5b,-3b,-b$$.

10. $$5x,-x,-3x,2x,-x$$.

11. $$26y,-11y,-15y,y,-3yx,2y$$.

12. $$5f,-9f,-3f,21f,-30f$$.

13. $$2s,-3s,s,-s,-5s,5s$$.

14. $$7y,-11y,16y,-3y,-2y$$.

15. $$5x,-7x,-2x,7x,2x,-5x$$.

16. $$7ab,-3ab,-5ab,2ab,ab$$.

Find the value of

17. $$-9x^2 + 11x^2 + 3x^2 -4x^2$$.

18. $$3a^2x - 18a^2x + a^2x$$.

19. $$3a^3 - 7a^3 - 8a^3 + 2a^3 - 11a^3$$.

20. $$4x^3 - 5x^3 - 8x^3 - 7x^3$$.

21. $$4a^2b^2 - a^2b^2 - 7a^2b^2 + 5a^2b^2 0a^2b^2$$.

22. $$-9x^4 - 4x^4 -12x^4 +13x^4 - 7x^4$$.

23. $$7abcd - 11abcd - 41abcd + 2abcd$$.

24. $$\tfrac{1}{2}x -\tfrac{1}{3}x + x \tfrac{2}{3}x$$.25. $$\tfrac{3}{2}a + \tfrac{3}{5}a - \tfrac{1}{2}a$$.

26. $$-5b + \tfrac{1}{4}b - \tfrac{3}{2} + 2b - \tfrac{1}{2}b + \tfrac{7}{4}b$$.

27. $$-\tfrac{5}{3}x^2-2x^2-\tfrac{2}{3}x^2+x^2+\tfrac{1}{2}x^2+\tfrac{11}{6}x^2$$.

28. $$-ab-\tfrac{1}{2}ab-\tfrac{1}{3}ab-\tfrac{1}{4}ab-\tfrac{1}{6}ab+\tfrac{5}{12}ab$$.

29. $$\tfrac{2}{3}x-\tfrac{3}{4}x^2-\tfrac{5}{6}x-2x+\tfrac{11}{6}x-\tfrac{1}{3}x+x$$.

30. $$-\tfrac{5}{3}x^2-\tfrac{3}{4}-\tfrac{4}{3}x^2-\tfrac{1}{4}x^2-x^2$$.