Đặt u=ex;v=f(x)" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 1px 0px; word-wrap: normal; word-break: break-word; display: inline-block; line-height: 0; font-size: 14.82px; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">u=ex;v=f(x)u=ex;v=f(x) thì ∫01u.v′dx+∫01v.u′dx=(u.v)|01" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 1px 0px; word-wrap: normal; word-break: break-word; display: inline-block; line-height: 0; font-size: 14.82px; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">1∫0u.v′dx+1∫0v.u′dx=(u.v)|10∫01u.v′dx+∫01v.u′dx=(u.v)|01
⇒∫01ex.f′(x)dx+∫01ex.f(x)dx=[ex.f(x)]|01" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 1px 0px; word-wrap: normal; word-break: break-word; display: inline-block; line-height: 0; font-size: 14.82px; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">⇒1∫0ex.f′(x)dx+1∫0ex.f(x)dx=[ex.f(x)]|10⇒∫01ex.f′(x)dx+∫01ex.f(x)dx=[ex.f(x)]|01
⇒∫01ex[f(x)+f′(x)]dx=e.f(1)−f(0)=e−1." role="presentation" style="box-sizing: border-box; margin: 0px; padding: 1px 0px; word-wrap: normal; word-break: break-word; display: inline-block; line-height: 0; font-size: 14.82px; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">⇒1∫0ex[f(x)+f′(x)]dx=e.f(1)−f(0)=e−1.⇒∫01ex[f(x)+f′(x)]dx=e.f(1)−f(0)=e−1.
Do đó a=1;b=−1⇒Q=0" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 1px 0px; word-wrap: normal; word-break: break-word; display: inline-block; line-height: 0; font-size: 14.82px; word-spacing: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">a=1;b=−1⇒Q=0