Question 4
Find two consecutive positive integers, sum of whose squares is 365.
We will use a quadratic equation to find the two consecutive positive integers.
Step 1 — Formulate the Equation
Let's assume the first positive integer is x. The next consecutive positive integer will be x + 1. The problem states the sum of their squares is 365. So, we can write the equation.
Let's expand the term .
Now, we combine like terms.
Let's move 365 to the left side.
We simplify the equation.
We can divide the entire equation by 2.
Step 2 — Solve the Equation
We need to solve this quadratic equation for x. Let's factorize the quadratic expression. We need two numbers that multiply to -182 and add up to 1. These numbers are 14 and -13.
Now, we factor by grouping terms.
We can factor out the common term .
This gives us two possible values for x. Either or .
The problem asks for positive integers. So, we must choose the positive value for x. Therefore, the first integer is 13. The second consecutive integer is .
The two consecutive positive integers are 13 and 14. Let's check our answer. . This is correct.
Answer
The two consecutive positive integers are 13 and 14.
More questions in Exercise 4.2
Find the roots of the following quadratic equations by factorisation:
(i)
(ii)
(iii)
(iv)
(v)
Solve the problems given in Example 1.
Find two numbers whose sum is 27 and product is 182.
Find two consecutive positive integers, sum of whose squares is 365.
The altitude of a right triangle is 7 cm less than its base. If the hypotenuse is 13 cm, find the other two sides.
A cottage industry produces a certain number of pottery articles in a day. It was observed on a particular day that the cost of production of each article (in rupees) was 3 more than twice the number of articles produced on that day. If the total cost of production on that day was ₹ 90, find the number of articles produced and the cost of each article.