COLUMBIA UNIVERSITY ELEMENTARY ALGEBRA COMPLETE

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Time: Three Hours

Six questions are required; two from Group A, two from Group B, and both questions of Group C. No extra credit will be given for more than six questions.

Group A

1. (a) Resolve the following into their prime factors:

(1)

(2)

(b) Find the H. C. F. and the L. C. M. of

2. (a) Simplify

(b) If prove that z is a mean proportional between x and y.

3. A crew can row 10 miles in 50 minutes downstream, and 12 miles in an hour and a half upstream. Find the rate of the current and of the crew in still water.

Group B

4. (a) Determine the values of k so that the equation

shall have equal roots.

(b) Solve the equations

(c) Plot the following two equations, and find from the graphs the approximate values of their common solutions:

5. Two integers are in the ratio Increase each by 15, and the difference of their squares is 999. What are the integers?

6. A man has $539 to spend for sheep. He wishes to keep 14 of the flock that he buys, but to sell the remainder at a gain of $2 per head. This he does and gains $28. How many sheep did he buy, and at what price each?

Group C

7. (a) Find the seventh term of

(b) Derive the formula for the sum of n terms of an arithmetic progression.

8. A ball falling from a height of 60 feet rebounds after each fall one third of its last descent. What distance has it passed over when it strikes the ground for the eighth time?


                                                                                                                                                                                                                                                                                                           

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