MP Board Class 11 Maths Solutions: Chapter 3 Relations and Functions
Welcome to Class 11 Mathematics: Chapter 3 Solutions
Hello Students! Welcome to our comprehensive step-by-step solution guide for MP Board Class 11 Mathematics Chapter 3: Relations and Functions. Mastering this chapter provides a strong foundation for Calculus and higher-level algebra. Below, you will find essential formulas followed by clean, step-by-step solutions for all main exercise problems.
Important Formulas & Concepts
- Cartesian Product: A × B = {(a, b) : a ∈ A and b ∈ B}
- Number of Elements: If n(A) = p and n(B) = q, then n(A × B) = p × q
- Total Number of Relations: Number of relations from A to B = 2p × q
- Domain: The set of all first elements in a relation R.
- Range: The set of all second elements in a relation R.
- Real Function: A function whose domain and range are subsets of Real Numbers (R).
Step-by-Step Textbook Solutions
Question 1: If (x/3 + 1, y - 2/3) = (5/3, 1/3), find the values of x and y.
Solution:
Since the ordered pairs are equal, their corresponding components must be equal.
1) Equating first components:
x/3 + 1 = 5/3
x/3 = 5/3 - 1 = 2/3
x = 2
2) Equating second components:
y - 2/3 = 1/3
y = 1/3 + 2/3 = 3/3
y = 1
Answer: x = 2 and y = 1
Question 2: If the set A has 3 elements and the set B = {3, 4, 5}, then find the number of elements in (A × B).
Solution:
Given: n(A) = 3
Set B = {3, 4, 5}, so n(B) = 3
We know that n(A × B) = n(A) × n(B)
n(A × B) = 3 × 3 = 9
Answer: The number of elements in (A × B) is 9.
Question 3: If G = {7, 8} and H = {5, 4, 2}, find G × H and H × G.
Solution:
1) G × H:
G × H = {(7, 5), (7, 4), (7, 2), (8, 5), (8, 4), (8, 2)}
2) H × G:
H × G = {(5, 7), (5, 8), (4, 7), (4, 8), (2, 7), (2, 8)}
Question 4: Find the domain and range of the real function f(x) = -|x|.
Solution:
Given function: f(x) = -|x|
1) Domain: |x| is defined for all real numbers x, so Domain = R (Set of Real Numbers).
2) Range: For any real number x, |x| ≥ 0. Multiplying by -1 gives -|x| ≤ 0.
Hence, f(x) yields only non-positive real values.
Range = (-∞, 0]
Question 5: Find the domain and range of the real function f(x) = √(9 - x²).
Solution:
1) Domain: For f(x) to be a real function, the quantity inside square root must be non-negative:
9 - x² ≥ 0 ⇒ x² ≤ 9 ⇒ -3 ≤ x ≤ 3
Domain = [-3, 3]
2) Range: For x ∈ [-3, 3], minimum value of y is √(9 - 3²) = 0 and maximum value is √(9 - 0²) = 3.
Range = [0, 3]
Question 6: A function f is defined by f(x) = 2x - 5. Write down the values of f(0), f(7), and f(-3).
Solution:
1) f(0) = 2(0) - 5 = 0 - 5 = -5
2) f(7) = 2(7) - 5 = 14 - 5 = 9
3) f(-3) = 2(-3) - 5 = -6 - 5 = -11
Question 7: Let f = {(1,1), (2,3), (0,-1), (-1,-3)} be a function from Z to Z defined by f(x) = ax + b. Determine a and b.
Solution:
Since (0, -1) ∈ f, we have f(0) = -1.
a(0) + b = -1 ⇒ b = -1
Since (1, 1) ∈ f, we have f(1) = 1.
a(1) + b = 1 ⇒ a + (-1) = 1 ⇒ a = 2
Answer: a = 2, b = -1
Summary & Wrap-Up
We hope these detailed step-by-step solutions help you build a clear conceptual understanding of Relations and Functions. Practicing domain, range, and Cartesian products will ensure high marks in your MP Board exams!
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