Question 1 (Textbook Exercise 7.1) — Identify Quadratic Equations
Quadratic: (a), (c), (d). Not quadratic: (b), (e), (f).
Every question in this chapter, answered and explained — step-by-step solutions drawn live from the chapter library across 3 question sections.
Question 1 (Textbook Exercise 7.1) — Identify Quadratic Equations
Quadratic: (a), (c), (d). Not quadratic: (b), (e), (f).
Question 2 (Textbook Exercise 7.1) — Solve by Factorization
Therefore, the roots of \(2x^2 + x - 6=0\) are \(x = -2\) and \(x = \frac{3}{2}\).
Question 3 (Textbook Exercise 7.1) — Solve by Completing the Square
Therefore, the roots of \(9x^2 - 15x + 6=0\) are \(x = 1\) and \(x = \frac{2}{3}\).
Question 4 (Textbook Exercise 7.1) — Solve by Using the Formula
Therefore, the roots of \(x^2 + 2x - 143=0\) are \(x = 11\) and \(x = -13\).
Question 5 (Textbook Exercise 7.1) — Word Problem — Marks
His marks were 13 in Mathematics and 17 in English, or 12 in Mathematics and 18 in English.
Question 6 (Textbook Exercise 7.1) — Word Problem — Playground
(a) Length 120 m, breadth 90 m. (b) 300 turfs. (c) Rs. 25,200.
Question 1 (Textbook Exercise 7.2) — Number Problem
The number is 5.
Question 2 (Textbook Exercise 7.2) — Number Problem
The number is \(\pm6\).
Question 3 (Textbook Exercise 7.2) — Number Problem
The number is 7.
Question 4 (Textbook Exercise 7.2) — Number Problem
The number is 3.
Question 5 (Textbook Exercise 7.2) — Number Problem
The number is \(\pm10\).
Question 6 (Textbook Exercise 7.2) — Number Problem
The number is \(\pm6\sqrt2\).
Question 7 (Textbook Exercise 7.2) — Number Problem
The number is 12.
Question 8 (Textbook Exercise 7.2) — Number Problem
The number is 8 (rejecting \(-9\) if a positive number is intended; both 8 and \(-9\) satisfy the equation algebraically).
Question 9 (Textbook Exercise 7.2) — Consecutive Even Numbers
The numbers are 8 and 10 (or \(-10\) and \(-8\)).
Question 10 (Textbook Exercise 7.2) — Consecutive Odd Numbers
The numbers are 3 and 5 (or \(-5\) and \(-3\)).
Question 11 (Textbook Exercise 7.2) — Reciprocal Problem
Therefore, the roots of \(3x^2 - 10x + 3=0\) are \(x = \frac{1}{3}\) and \(x = 3\).
Question 12 (Textbook Exercise 7.2) — Two Natural Numbers
The numbers are 6 and 15.
Question 13 (Textbook Exercise 7.2) — Ages of Two Brothers
The ages are 17 years and 13 years.
Question 14 (Textbook Exercise 7.2) — Present Ages of Two Brothers
Their present ages are 12 years and 10 years.
Question 15 (Textbook Exercise 7.2) — Ages of Two Sisters
Their present ages are 15 years and 12 years.
Question 16 (Textbook Exercise 7.2) — Age-Product Problems (4 parts)
(a) 7 years ago.
Question 17 (Textbook Exercise 7.2) — Geometry Problems (5 parts)
(a) The remaining sides are 24 m and 7 m.
Question 18 (Textbook Exercise 7.2) — Two-Digit Number
The number is 24.
Question 19 (Textbook Exercise 7.2) — Pencil Distribution
(a) 20 students were enrolled. (b) Each student received 12 pencils.
Section C — Additional SEE-Style Practice
SEE Practice 1 — Direct Factorization
Therefore, the roots of \(x^2 - 8x + 15=0\) are \(x = 3\) and \(x = 5\).
SEE Practice 2 — Direct Formula
Therefore, the roots of \(4x^2 - 4x - 3=0\) are \(x = \frac{3}{2}\) and \(x = - \frac{1}{2}\).
SEE Practice 3 — Completing the Square
Therefore, the roots of \(x^2 - 4x + 1=0\) are \(x = \sqrt{3} + 2\) and \(x = 2 - \sqrt{3}\).
SEE Practice 4 — Word Problem (Numbers)
The number is 11 (rejecting \(-12\) if a positive number is required).
SEE Practice 5 — Word Problem (Ages)
Daughter's age is 7 years, mother's age is 25 years.
SEE Practice 6 — Word Problem (Right Triangle)
The two sides are 8 m and 15 m.