Solution
Related Formula
(1 - 2x)²⁶ = Σr=0²⁶ 26r (-2x)^rThe coefficient extraction utilizes the distributive property over the polynomial (ax²+bx+c).
Core Logic
Expansion of expression: (ax² + bx + c) Σr=0²⁶ 26r (-2x)r
For the term in x², we pick contributions yielding total power 2: a · (x⁰ term of sum) + b · (x¹ term) + c · (x² term) = 0 a · 260(-2)⁰ + b · 261(-2)¹ + c · 262(-2)² = 0 a - 52b + 1300c = 0 (1)
Step 1: Formulate the system of linear equations
For the term in x³ (set to 0): a · (x¹ term) + b · (x² term) + c · (x³ term) = 0 a · 261(-2)¹ + b · 262(-2)² + c · 263(-2)³ = 0 -52a + 1300b - 20800c = 0 (2)
For the term in x¹ (set to -56): b · (x⁰ term) + c · (x¹ term) = -56 b · 260(-2)⁰ + c · 261(-2)¹ = -56 b - 52c = -56 (3)
Step 2: Solve the Linear System
From (3), b = 52c - 56. Substitute into (2) divided by -52 to simplify: a - 25b + 400c = 0. Substitute into (1): a - 52b + 1300c = 0. Subtracting: 27b - 900c = 0 ⇒ b = (100)/(3)c. Wait, recalculating directly: From (2): -52a + 1300b - 20800c = 0 ⇒ a - 25b + 400c = 0. From (1): a - 52b + 1300c = 0. (a - 25b + 400c) - (a - 52b + 1300c) = 0 ⇒ 27b - 900c = 0 ⇒ 3b = 100c. Substitute into (3): b - 52(3b/100) = -56 ⇒ fractional results? Let's check coefficients accurately. 263(-2)³ = (26 · 25 · 24)/(6) × (-8) = 2600 × -8 = -20800. Divide by -52: a - 25b + 400c = 0. Correct. (a - 52b + 1300c) - (a - 25b + 400c) = -27b + 900c = 0 ⇒ 27b = 900c ⇒ b = (100)/(3)c. This contradicts integer expectations. Let's substitute b from (3) directly. b = 52c - 56. 27(52c - 56) = 900c 1404c - 1512 = 900c ⇒ 504c = 1512 ⇒ c = 3. Then b = 52(3) - 56 = 156 - 56 = 100. From (1): a - 52(100) + 1300(3) = 0 ⇒ a - 5200 + 3900 = 0 ⇒ a = 1300.
Step 3: Compute final value
We have a = 1300, b = 100, c = 3.
a + b + c = 1300 + 100 + 3 = 1403Pattern Recognition
Polynomial-Binomial product coefficient extractions strictly generate cascaded linear Diophantine-style equations. Solving from the lowest degree constraint (x¹) upward sequentially unwinds the system cleanly.
Chapter Mix
Class 11 Maths: Binomial Theorem