NumericalModerate3 marks
The product of two consecutive natural numbers which are multiples of 3 is equal to 810. Find the two numbers.
Topic: Quadratic word problems
Previous-year question practice database
Answer
Exam answer
Let the smaller multiple of 3 be x. The next is x+3.
x(x+3)=810 x²+3x−810=0 (x−27)(x+30)=0.
Natural numbers give x=27.
Answer: 27 and 30.
Explanation
Consecutive multiples of 3 differ by 3. Reject the negative root.
More from Solving (simple) Problems (Based on Quadratic Equations)
The difference of two natural numbers is 5 and sum of their reciprocals is 3/10 . Find the two numbers.2026the original speed of the car.2025with the reduced speed, the number of hours they took to reach their destination.2025A man covers a distance of 100 km, travelling with a uniform speed of x km/hr. Had the speed been 5 km/hr more it would have taken 1 hour less. Find x the original speed.2023The number of litres of diesel used by car X is:2021The number of litres of diesel used by car Y is:2021