1A. 8
a = 2(-2)^2 - 3(1) + 1/2(6)
a = 2(4) - 3 + 3
a = 8 - 3 + 3
a = 8
1B. 18
20 = 2(6)^2 - 3c + 1/2(4)
20 = 2(36) - 3c + 2
20 = 72 - 3c + 2
20 = 74 - 3c
-54 = - 3c
c = 18
2. 10x - x^2
First, find the area of the triangle. Remember, the area of a triangle is 1/2(b)(h).
A(triangle) = 1/2(2x)(10)
A(triangle) = 10x
Second, find the area of the square. The area of a square is (b)(h).
A(square) = (x)(x)
A(square) = x^2
Lastly, subtract the area of the square from the area of the rectangle to find the area of the shaded region in terms of x.
A(shaded area) = 10x - x^2
Hope this helps!