If I1∫π0sin884xsin1122xsinxdx and I2∫10x238(x1768−1)x2−1dx, then I1I2 is equal to
2
If I1∫π0sin884xsin1122xsinxdx=∫π0cos238xsinxdx−∫π0cos2006xsinxdx
Let I2m=∫π0cos2mxsinxdxthenI2m−I2m−2=∫π0cos2mx−cos(2m−2)xsinxdx=2(cos(2m−1)x2m−1)π0=−42m−1∴ I2006−I2=−4(13+15+…+12005) & I238−I2=−4(13+15+…+1237)2I1=4(1239+1241+…+12005)
Now,
I2=∫10(x238+x240+…+x2004)dx=(1239+1241+…)∴I1I2=2