∫上限2,下限-1 |2x|dx
=∫[-1,2]|2x|dx
=∫[-1,0]-2xdx+∫[0,2]2xdx
=-x^2|[-1,0]+x^2|[0,2]
=-[0^2-(-1)^2]+2^2-0^2
=-(0-1)+4-0
=1+4
=5