Solve the problem.
-A formula for the focal length of a lens is $f = \frac { a b } { b + a }$ Calculate f (the focal length)for a = 8 cm and b = 11 cm. Round to the nearest tenth of a centimeter when necessary.
A)4.0 cm
B)5.5 cm
C)3.4 cm
D)4.6 cm

Question

Quizplus · Accepted Answer

Plugging the values into the formula $f = \frac{ab}{b + a}$ gives $f = \frac{8 \times 11}{11 + 8} = \frac{88}{19}$, which calculates to approximately 4.6 cm when rounded to the nearest tenth.

Solve the Problem f=abb+af = \frac { a b } { b + a }f=b+aab​

Solve the Problem $f = \frac { a b } { b + a }$