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# Can someone show me how to solve for r?

(1/(1+r)) * (29.4/r) - 102.7 = 0

### 1 Answer

- 1 decade agoFavorite Answer
Add 102.7 to both sides

(1/(1+r)) * (29.4/r) = 102.7

multiply (1/(1+r)) * (29.4/r)

29.4/[(1+r)(r)] = 102.7

Expand the denominator

29.4/[(r + r^2)] = 102.7

Multiply both sides by [(r + r^2)

29.4 = 102.7(r + r^2)

Expand 102.7(r + r^2)

29.4 = 102.7r + 102.7r^2

subtract 29.4 from both sides.

0 = 102.7r + 102.7r^2 - 29.4

Use the quadratic formula to find r.

http://www.purplemath.com/modules/quadform.htm - this site shows the formula.

input the numbers into the formula and it will give you your r values.

-102.7 + sqt(102.7^2 - 4*102.7*-29.4)

----------------------------------------------- = r

2 * 102.7

r = ~-0.49197...

-102.7 - sqt(102.7^2 - 4*102.7*-29.4)

----------------------------------------------- = r

2 * 102.7

r = ~2.53169...

hope I got all the numbers right and I hope this helps

Source(s): http://www.purplemath.com/modules/quadform.htm math class