Given that [tex]\(\frac{1}{u} + \frac{1}{v} = \frac{1}{f}\)[/tex]:

a. Find [tex]\(u\)[/tex] if [tex]\(v = 6\)[/tex] and [tex]\(f = 2\)[/tex].

b. Find [tex]\(v\)[/tex] if [tex]\(u = 4\)[/tex] and [tex]\(f = 2\)[/tex].

c. Make [tex]\(f\)[/tex] the subject of the formula.



Answer :

Sure, let's solve the given problems step by step.

### Given:
[tex]\[ \frac{1}{u} + \frac{1}{v} = \frac{1}{f} \][/tex]

### Part (a): Find [tex]\( u \)[/tex] if [tex]\( v = 6 \)[/tex] and [tex]\( f = 2 \)[/tex]

Given:
- [tex]\( v = 6 \)[/tex]
- [tex]\( f = 2 \)[/tex]

We need to find [tex]\( u \)[/tex].

Substitute the known values into the given equation:
[tex]\[ \frac{1}{u} + \frac{1}{6} = \frac{1}{2} \][/tex]

Rearrange to isolate [tex]\( \frac{1}{u} \)[/tex]:
[tex]\[ \frac{1}{u} = \frac{1}{2} - \frac{1}{6} \][/tex]

Find a common denominator:
[tex]\[ \frac{1}{2} = \frac{3}{6} \][/tex]

So,
[tex]\[ \frac{1}{u} = \frac{3}{6} - \frac{1}{6} = \frac{2}{6} = \frac{1}{3} \][/tex]

Therefore,
[tex]\[ u = 3 \][/tex]

### Part (b): Find [tex]\( v \)[/tex] if [tex]\( u = 4 \)[/tex] and [tex]\( f = 2 \)[/tex]

Given:
- [tex]\( u = 4 \)[/tex]
- [tex]\( f = 2 \)[/tex]

We need to find [tex]\( v \)[/tex].

Substitute the known values into the given equation:
[tex]\[ \frac{1}{4} + \frac{1}{v} = \frac{1}{2} \][/tex]

Rearrange to isolate [tex]\( \frac{1}{v} \)[/tex]:
[tex]\[ \frac{1}{v} = \frac{1}{2} - \frac{1}{4} \][/tex]

Find a common denominator:
[tex]\[ \frac{1}{2} = \frac{2}{4} \][/tex]

So,
[tex]\[ \frac{1}{v} = \frac{2}{4} - \frac{1}{4} = \frac{1}{4} \][/tex]

Therefore,
[tex]\[ v = 4 \][/tex]

### Part (c): Make [tex]\( f \)[/tex] the subject of the formula

Given:
[tex]\[ \frac{1}{u} + \frac{1}{v} = \frac{1}{f} \][/tex]

We need to solve for [tex]\( f \)[/tex].

Rearrange the equation:
[tex]\[ \frac{1}{f} = \frac{1}{u} + \frac{1}{v} \][/tex]

To solve for [tex]\( f \)[/tex], take the reciprocal of both sides:
[tex]\[ f = \frac{1}{\frac{1}{u} + \frac{1}{v}} \][/tex]

So the formula for [tex]\( f \)[/tex] is:
[tex]\[ f = \frac{1}{\frac{1}{u} + \frac{1}{v}} \][/tex]

Thus, summarizing all parts:

a. [tex]\( u = 3 \)[/tex] when [tex]\( v = 6 \)[/tex] and [tex]\( f = 2 \)[/tex]

b. [tex]\( v = 4 \)[/tex] when [tex]\( u = 4 \)[/tex] and [tex]\( f = 2 \)[/tex]

c. [tex]\( f = \frac{1}{\frac{1}{u} + \frac{1}{v}} \)[/tex]