The ratio of two positive numbers is 3:4. The sum of their squares is 400. What will be the sum of the numbers? And the options are a. 28, b. 27, c. 22, d. 24. I can do the try and error but I want to know whether the sum of both numbers always be the multiple of 7 (3+4)? Hence the answer would be 28?
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we have $$\frac{a}{b}=\frac{3}{4}$$ and $$a^2+b^2=400$$ from the first condition we get $$a=\frac{3}{4}b$$ plugging this in the second equation we obtain $$\frac{9}{16}b^2+b^2=400$$ Can you finish? ok then write $$\frac{9}{16}b^2+\frac{16}{16}b^2=400$$ and we get $$\frac{25}{16}b^2=400$$ and now?
Dr. Sonnhard Graubner
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Actually, I'm pretty beginner in mathematics. I'm learning it by myself. I don't know how to finish this. – Jigar Trivedi Jul 09 '17 at 17:36
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(5/4)*b =20 --> b=80/5 – Jigar Trivedi Jul 09 '17 at 18:33
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b=16. Thanks. I have two question. 1. How did you get (16/16)*b in fifth step? And whether the sum of both numbers always be the multiple of 7 (3+4)? Hence the answer would be 28? – Jigar Trivedi Jul 09 '17 at 18:41