The area of the trapezoid is ((2 + y)/2)*x --->>> ( (2+x/2+2)/2)*x = A(x) --->>> A(x) = 2x+x2/4
A(0) = 2*0+0/4 = 0 So A(0)=0 A(1) = 2*1+1/4=2.25 so A(1) = 2.25 and A(2)=2*2 + 4/4 = 5 So A(2)=5
A(3)=2*3+9/4 = 6+2.25 = 8.25 So A(3)=8.25
A(3)-A(1) = 8.25-2.25 = 6