Int(1 + e ^(2x))^(1/2)dx的积分是多少?

Int(1 + e ^(2x))^(1/2)dx的积分是多少?
Anonim

回答:

#1 / -ln(ABS(SQRT(1 + E ^(2×))+ 1))+ LN(ABS(SQRT(1 + E ^(2×)) - 1)) + SQRT(1 + E ^(2×))+ C#

说明:

首先我们替换:

#U = E 1(2×)1; E 1(2×)= U-1#

#(DU)/(DX)= 2E ^(2×); DX =(DU)/(2E ^(2×))#

#intsqrt(U)/(2E ^(2×))杜= intsqrt(U)/(2(U-1))杜= 1 / 2intsqrt(U)/(U-1)杜#

执行第二次替换:

·V ^ 2 = U; V = SQRT(U)#

#2V(DV)/(DU)= 1;杜= 2vdv#

#1 / 2intv /(V ^ 2-1)2vdv = INTV ^ 2 /(V ^ 2-1)的dv = INT1 + 1 /(V ^ 2-1)的dv#

使用部分分数拆分:

#1 /((V + 1)(V-1))= A /(V + 1)+ B /(V-1)#

#1 = A(V-1)+ B(V + 1)#

#V = 1#:

#1 = 2B#, #B = 1 /#

#V = -1#:

#1 = -2A#, #A = -1 / 2#

现在我们有:

#-1 /(2(V + 1))+ 1 /(2(V-1))#

#INT1 + 1 /((V + 1)(V-1))的dv = int1-1 /(2(V + 1))+ 1 /(2(V-1))的dv = 1/2 -ln (ABS(v + 1))+ LN(ABS(v-1)) + v + C#

替换回来 #V = SQRT(U)#:

#1 / -ln(ABS(SQRT(U)+1))+ LN(ABS(SQRT(U)-1)) + SQRT(U)+ C#

替换回来 #U = 1 + E ^(2×)#

#1 / -ln(ABS(SQRT(1 + E ^(2×))+ 1))+ LN(ABS(SQRT(1 + E ^(2×)) - 1)) + SQRT(1 + E ^(2×))+ C#