Answer :
Let's solve for [tex]\( r \)[/tex] in the given equation:
[tex]\[ \frac{f}{r^2} + a = n + k \][/tex]
To isolate [tex]\( r \)[/tex], let's follow these steps:
1. Subtract [tex]\( a \)[/tex] from both sides:
[tex]\[ \frac{f}{r^2} = n + k - a \][/tex]
2. Isolate [tex]\( r^2 \)[/tex] by multiplying both sides by [tex]\( r^2 \)[/tex]:
[tex]\[ f = (n + k - a)r^2 \][/tex]
3. Divide both sides by [tex]\( (n + k - a) \)[/tex]:
[tex]\[ r^2 = \frac{f}{n + k - a} \][/tex]
4. Take the square root of both sides to solve for [tex]\( r \)[/tex]:
[tex]\[ r = \pm \sqrt{\frac{f}{n + k - a}} \][/tex]
The solutions for [tex]\( r \)[/tex] are:
[tex]\[ r = \pm \sqrt{\frac{f}{n + k - a}} \][/tex]
Given the provided choices, the correct answer is:
[tex]\[ \boxed{\pm \sqrt{\frac{f}{n+k-a}}} \][/tex]
[tex]\[ \frac{f}{r^2} + a = n + k \][/tex]
To isolate [tex]\( r \)[/tex], let's follow these steps:
1. Subtract [tex]\( a \)[/tex] from both sides:
[tex]\[ \frac{f}{r^2} = n + k - a \][/tex]
2. Isolate [tex]\( r^2 \)[/tex] by multiplying both sides by [tex]\( r^2 \)[/tex]:
[tex]\[ f = (n + k - a)r^2 \][/tex]
3. Divide both sides by [tex]\( (n + k - a) \)[/tex]:
[tex]\[ r^2 = \frac{f}{n + k - a} \][/tex]
4. Take the square root of both sides to solve for [tex]\( r \)[/tex]:
[tex]\[ r = \pm \sqrt{\frac{f}{n + k - a}} \][/tex]
The solutions for [tex]\( r \)[/tex] are:
[tex]\[ r = \pm \sqrt{\frac{f}{n + k - a}} \][/tex]
Given the provided choices, the correct answer is:
[tex]\[ \boxed{\pm \sqrt{\frac{f}{n+k-a}}} \][/tex]