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Find-L-tcosh2t-




Question Number 16493 by Sai dadon. last updated on 23/Jun/17
Find L{tcosh2t}
FindL{tcosh2t}
Commented by prakash jain last updated on 23/Jun/17
∫_0 ^∞ tcosh 2te^(−st) dt  =∫_0 ^( ∞) t((e^(2t) +e^(−2t) )/2)e^(−st) dt  =(1/2)[∫_0 ^( ∞) te^((2−s)t) dt+∫_0 ^∞ te^(−(s+2)t) dt]  =(1/2)[((te^((2−s)t) )/(2−s))−(e^((2−s)t) /((2−s)^2 ))−((te^(−(2+s)t) )/(2+s))−(e^(−(s+2)t) /((s+2)^2 ))]_0 ^∞   =(1/2)[(1/((2−s)^2 ))+(1/((2+s)^2 ))]  =(((2+s)^2 +(2−s)^2 )/(2(s^2 −4)^2 ))=((s^2 +4)/((s^2 −4)^2 ))
0tcosh2testdt=0te2t+e2t2estdt=12[0te(2s)tdt+0te(s+2)tdt]=12[te(2s)t2se(2s)t(2s)2te(2+s)t2+se(s+2)t(s+2)2]0=12[1(2s)2+1(2+s)2]=(2+s)2+(2s)22(s24)2=s2+4(s24)2

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