The above expression is not in its simplest form, and we need to simplify it, that is what asked in the question.
Given equation,

First of all, let's open the parentheses to combine the like terms for simplifying.

Arranging the like terms, x² with x², x with x and constant terms near to each other.

Simplying further,


So, the correct option is C
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You just have to go 7x28=[7x20]+[7x8]=196
Pi/3 is equivalent to 60 degrees, as 2pi is equal to 360 degrees. cos(60) in a triangle yields 1/2, and sin(60) yields (3^(1/2))/2. Thus, -pi/3, or -60 degrees would be a fourth quadrant point on the unit circle and these values would be negative as well, at cos(-pi/3)=-1/2 and sin(-pi/3)=-(3^(1/2))/2