Question

Rearrange the formula to make a) f the subject and b) v the subject. 1/v+1/u=1/f

Answer 1

see explanation

Explanation:

Multiply through by the lowest common multiple of u, v and f, that is uvf

uvf ×
`(1)/(v)` + uvf ×
`(1)/(u)` = uvf ×
`(1)/(f)`, that is

uf + vf = uv ← factor out f on the left side → (1)

f(u + v) = uv ← divide both sides by (u + v)

f =
`(uv)/(u+v)`

(b)

Using line (1)

uf + vf = uv ( subtract uv from both sides )

uf + vf - uv = 0 ( subtract uf from both sides )

vf - uv = - uf ← factor out v on the left side

v(f - u) = - uf ← divide both sides by (f - u)

v = -
`(uf)/(f-u)`

Answer 2

What’s 2 square or 3 Firth’s