Write the expanded form of $$(9a + 4b + 5c)^2$$​​

Correct option is C

Given: ​

​$$(9a + 4b + 5c)^2$$ 

Formula Used: 

​$$(a + b+c)^2 = a^2 + b^2 +c^2 + 2ab+2bc+2ac$$ 

Solution: ​

​$$(9a + 4b + 5c)^2 \\ \ \\ = (9a)^2 + (4b)^2 +(5c)^2 + 2\times 9a \times 4b +2\times 4b \times5c +2\times 5c \times 9a \\ \ \\ = 81a^2+16b^2+25c^2+72ab+40bc+90ac$$​​