The bases of an isosceles trapezoid are represented by 4x and 2x.. the height of the trapezoid is represented by (x − 6). which polynomial expression best represents the area of the trapezoid?
a) 3x2 − 18x
b) 3x2 + 18x
c) 3x − 18
d) 6x2 + 36x

The area of a trapezoid is calculated by the equation,
                          A = 0.5(b₁ + b₂)h
where b₁ and b₂ are the bases and h is the height. When we substitute the given expression for the dimensions in the given,
                          A = 0.5(4x + 2x)(x - 6)
                          A = 0.5(6x)(x - 6) = 3x² - 18
Thus, the answer is letter A.