Question

The number 15 is the geometric mean of 25 and what other number?​

Answer 1

Answer:

9

Step-by-step explanation:

$\text{The geometric mean of two numbers}\ a\ \text{and}\ b:\\\\M=\sqrt{(a)(b)}\\\\\text{We have}\\\\M=15,\ a=25\\\\\text{substitute:}\\\\15=\sqrt{25b}\qquad\text{square of both sides}\\\\15^2=(\sqrt{25b})^2\\\\225=25a\qquad\text{divide both sides by 25}\\\\\dfrac{225}{25}=\dfrac{25b}{25}\\\\9=b\to b=9$