McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
1. Geometric Mean
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Exercise 45 Page 626

Let x and x+1 be two consecutive positive integers. Evaluate the geometric mean and the mean of these two numbers and check if they are equal.

Never

Practice makes perfect

We are asked to determine if the geometric mean and the mean are equal for two consecutive positive integers. Let's recall the formulas for the geometric mean and the mean of two positive integers a and b.

Geometric mean: sqrt(a* b)
Mean: a+ b/2
Let x and x+1 be two consecutive positive integers. Our next step will be to evaluate both means for these numbers and check if they are equal. We will start with the geometric mean.
sqrt(a* b)
sqrt(x*( x+1))
sqrt(x^2+x)
Next, let's evaluate the arithmetic mean.
a+b/2
x+ x+1/2
â–Ľ
Simplify
2x+1/2
2x/2+1/2
x+0.5
Let's set these two expressions together and check if they are equal.
sqrt(x^2+x)? =x+0.5
â–Ľ
Solve for x
(sqrt(x^2+x))^2? =(x+0.5)^2
x^2+x? =(x+0.5)^2
x^2+x? =x^2+2* x*0.5+0.5^2
x^2+x? =x^2+x+0.5^2
x^2+x? =x^2+x+0.25
x? =x+0.25
0≠0.25
Since we ended with a false statement, we can say that the geometric mean for consecutive integers is never the mean of the two numbers.