Answer:
x = [tex]\frac{ab}{b+a}[/tex]
Step-by-step explanation:
Given
[tex]\frac{1}{a}[/tex] + [tex]\frac{1}{b}[/tex] = [tex]\frac{1}{x}[/tex] ( express the sum on the left as a single fraction )
[tex]\frac{b+a}{ab}[/tex] = [tex]\frac{1}{x}[/tex] ( cross- multiply )
x(b + a) = ab ← divide both sides by (b + a)
x = [tex]\frac{ab}{b+a}[/tex]
