Question

Find the square of ( 3a - 2b - 5c )

Answer 1

Answer:

9a^2 + 4b^2 + 25c^2 - 12ab + 20bc - 30ca

Step-by-step explanation:

Note:

• ( a + b + c )^2 = a^2 + b^2 + c^2 + 2ab + 2bc + 2ca
• + × + = +
• + × - = -
• - × - = +
• - × + = -

Given

( 3a - 2b - 5c ) ^2

where a = 3a, b = ( -2b ) , c = ( - 5c )

( 3a - 2b - 5c ) ^2

=> (3a)^2 + (-2b)^2 + (-5c)^2 + 2(3a)(-2b) + 2(-2b)(-5c) + 2 (-5c)(3a)

=> 9a^2 + 4b^2 + 25c^2 - 12ab + 20bc - 30ca