The graph of y=−8x2+6x−1 will be as shown

Now ∫01[−8x2+6x−1]dx=∫041(−1)dx+∫4121(0)dx+∫2143(−1)dx
+∫4383+17(−2)dx+∫83+171(−3)dx
=−[x]041+0−[x]2143+−2[x]4383+17−3[x]83+171
=−(41−0)−(43−21)−2(83+17−43)−3(1−83+17)
=−41−41+8−6−217+23−3+89+317
=817−13