Site navigation

The difference of ages of a mother and daughter is 21 and the product of their ages is equal to 72.…

Let the daughter's age be \(d\), so the mother's age is \(d+21\) and \(d(d+21)=72\). This gives \(d^{2}+21d-72=0\), which factorises as \((d+24)(d-3)=0\). The positive root…

Choose your answer

The difference of ages of a mother and daughter is 21 and the product of their ages is equal to 72. Find the daughter's age?

Select one answer
Answer and explanation

Correct answer A

Let the daughter's age be dd, so the mother's age is d+21d+21 and d(d+21)=72d(d+21)=72. This gives d2+21d−72=0d^{2}+21d-72=0, which factorises as (d+24)(d−3)=0(d+24)(d-3)=0. The positive root is d=3d=3, so the daughter is 3 years old.

Practice for these exams

Related question papers

Related exam syllabi

Related questions in this topic