Question

20: a = 5 and b = -5, then their harmonic mean is:
(a) -5
(b) 5
(c)0​

Answer 1

Answer:

Option (C) is correct

Zero is the answer

I hope it's help you

Answer 2

Answer:

Required harmonic mean of a and b is 0.

So, option c is the correct answer.

Step-by-step explanation:

Here given,

$a = 5 \\ b = ( - 5)$

We want to find here harmonic mean of a and b.

But question is what is harmonic mean.

If x and y are two numbers then harmonic mean of x and y will be $\frac{1}{x} + \frac{1}{y}$

For example we are taking two numbers 2 and 3.

Now,harmonic mean of 2 and 3 is

$\frac{1}{2} + \frac{1}{3} \\ = \frac{3 + 2}{6} \\ = \frac{5}{6}$

Here given two numbers are 5 and (-5).

So harmonic mean of 5 and (-5) is

$\frac{1}{5} + \frac{1}{( - 5)} \\ = \frac{1}{5} - \frac{1}{5} \\ = 0$

This is a problem of Algebra.

Some important Algebra formulas.

(a + b)² = a² + 2ab + b²

(a − b)² = a² − 2ab − b²

(a + b)³ = a³ + 3a²b + 3ab² + b³

(a - b)³ = a³ - 3a²b + 3ab² - b³

a³ + b³ = (a + b)³ − 3ab(a + b)

a³ - b³ = (a -b)³ + 3ab(a - b)

a² − b² = (a + b)(a − b)

a² + b² = (a + b)² − 2ab

a² + b² = (a − b)² + 2ab

a³ − b³ = (a − b)(a² + ab + b²)

a³ + b³ = (a + b)(a² − ab + b²)

Know more about Algebra,

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