Question

Expand :(2a-5b-4c) ²

Answer 1

Heya !!!

( 2A - 5B - 4C )²

=> { 2A + ( -5B) + ( -4C) }²

As we know that,

( A + B + C)² = ( A)² + ( B)² + (C)² + 2AB + 2BC + 2CA.

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=> ( 2A)² + (-5B)² + ( -4C)² + 2 × 2A × ( -5B) + 2 × (-5B) × (-4C) + 2 × (-4C) × ( 2A)

=> 4A² + 25B² + 16C² - 20AB + 40BC - 16CA.

HOPE IT WILL HELP YOU..... :-)

Answer 2

Hi,

Here is your answer,

( 2a-5b-4c )²
 → [2a+(-5b)+(-4c)²]            { EXPANDING }
→ (2a)² + (-5b)² + (-4c)² + 2.2a.(-5b) + 2.(-5b) × (-4c) + 2 .(-4c).( 2c)
→ (4a)² + (25b)² + (16c)² - 20ab + 40bc - 16ca.

FORMULA APPLIED:- ( a+b+c)² = (a)² + (b)²+ (c)² + 2ab+2bc+2ca