Why they took mod for region [0, 2]?????

EXAMPLE 5 Find the area of the region between the x-axis and the graph of fx) = * -x*-2x, -1 sx<2. Area= y =x*- x-2x Solution First find the zeros of f. Since fx) = **-x-2x = xt*- x - 2) = xr + 1) 2). the zeros are x = 0, -1, and 2 (Fig. 4.24). The zeros partition [-1, 2] into two subintervals: [-1, 0], on which f>0 and [0, 2], on which f < 0. We integrate f over each subinterval and add the absolute values of the calculated values. -20 Integral over [-1,0}: 4.24 The region between the curve y=*-x-2x and the x-axis (Example 5). --- --20)dr -i Integral over [0, 2]: -0- Total enclosed area = -- Enclosed area: