1/4∫0 √x1−2xdx Đặt t=√x=>t2=x=>2tdt=dxx 0 1/4t 0 1/2= 1/2∫0t.2t.dt√1−2t2Đặt t=1√2sinu=>dt=1√2cosu.dut 0 1/2u 0 Π/4= Π/4∫02(1√2sinu)21√2cosu.du√1−sin2u= Π/4∫0sin2u.1√2.du
1/4∫0 √x1−2xdx Đặt
t=√x=>t2=x=>2tdt=dxx 0 1/4t 0 1/2=
1/2∫0t.2t.dt√1−2t2Đặt
t=1√2sinu=>dt=1√2cosu.dut 0 1/2u 0
Π/4=
Π/4∫02(1√2sinu)21√2cosu.du√1−sin2u=
Π/4∫0sin2u.1√2.du= 1√2Π/4∫01−cos2x2.du=12√2(u−12sin2u)|Π/40 =Π−28√2