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Q3:
Find two numbers whose sum is $27$ and product is $182$.
Solution :
Given:
1. The sum of two numbers is $27$.
2. The product of the same two numbers is $182$.
To Find:
The two numbers.
Step 1: Defining the Variables
Let the first number be $x$.
Since the sum of the two numbers is $27$, the second number can be expressed as $(27 - x)$.
Step 2: Formulating the Quadratic Equation
According to the problem, the product of these two numbers is $182$. Therefore, we can set up the following equation:
$x(27 - x) = 182$
Step 3: Simplifying the Equation
Distribute $x$ into the parentheses:
$27x - x^2 = 182$
Rearrange the terms to form a standard quadratic equation of the form $ax^2 + bx + c = 0$:
$-x^2 + 27x - 182 = 0$
Multiply the entire equation by $-1$ to make the leading coefficient positive:
$x^2 - 27x + 182 = 0$
Step 4: Solving by Factorization (Splitting the Middle Term)
We need to find two numbers that multiply to $182$ and add up to $-27$.
Prime factorization of $182$:
$182 = 2 \times 91 = 2 \times 7 \times 13 = 14 \times 13$
Since the sum must be $-27$, we choose $-14$ and $-13$ because $(-14) + (-13) = -27$ and $(-14) \times (-13) = 182$.
Rewrite the middle term:
$x^2 - 14x - 13x + 182 = 0$
Step 5: Grouping and Factoring
Group the terms:
$(x^2 - 14x) - (13x - 182) = 0$
Factor out the common terms from each group:
$x(x - 14) - 13(x - 14) = 0$
Factor out the common binomial $(x - 14)$:
$(x - 14)(x - 13) = 0$
Step 6: Finding the Roots
Set each factor to zero [Using the Zero Product Property]:
Case 1: $x - 14 = 0 \implies x = 14$
Case 2: $x - 13 = 0 \implies x = 13$
If the first number is $14$, the second number is $27 - 14 = 13$.
If the first number is $13$, the second number is $27 - 13 = 14$.
Final Answer: The two numbers are 13 and 14.
More Questions from Class 10 Mathematics Quadratic Equations EXERCISE 4.2
- Q1(i): Find the roots of the following quadratic equations by factorisation: (i) $x^2 – 3x – 10 = 0$
- Q1(ii): Find the roots of the following quadratic equations by factorisation: (ii) $2x^2 + x – 6 = 0$
- Q1(iii): Find the roots of the following quadratic equations by factorisation: (iii) $\sqrt{2}x^2 + 7x + 5\sqrt{2} = 0$
- Q1(iv): Find the roots of the following quadratic equations by factorisation: (iv) $2x^2 – x + \frac{1}{8} = 0$
- Q1(v): Find the roots of the following quadratic equations by factorisation: (v) $100x^2 – 20x + 1 = 0$
- Q2: Solve the problems given below. Represent the following situations mathematically: (i) John and Jivanti together have 45 marbles. Both of them lost 5 marbles each, and the product of the number of marbles they now have is 124. We would like to find out how many marbles they had to start with. (ii) A cottage industry produces a certain number of toys in a day. The cost of production of each toy (in rupees) was found to be 55 minus the number of toys produced in a day. On a particular day, the total cost of production was Rs.750. We would like to find out the number of toys produced on that day.
- Q4: Find two consecutive positive integers, sum of whose squares is $365$.
- Q5: The altitude of a right triangle is $7$ cm less than its base. If the hypotenuse is $13$ cm, find the other two sides.
- Q6: 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.
CBSE Solutions for Class 10 Mathematics Quadratic Equations
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