Question

(t-7)u5(t)-(t-5)u7(t) Laplace Function. I get s^-2[(1-s)e^-5s - (1+s)e^-7s] but it is wrong.

Answer 1

that is the exact question

Answer 2

ty

Answer 3

im getting:\[\frac{ (1 - 12s)e^{5s} + (12s - 1)e^{7s} }{ s^2 }\]

Answer 4

i used this beautiful table: applied #30 to #25
http://tutorial.math.lamar.edu/pdf/Laplace_Table.pdf

Answer 5

ok that makes more sense now
i didn't know which one to apply thanks

Answer 6

glad i could help ^_^

Answer 7

are we sure that's the right answer yet? I'm not getting the 12's...

Answer 8

i think so,

Answer 9

what are you getting, i am redoing the problem right now

Answer 10

you can write this\[(t-5)u_5(t)-2u_5(t)-(t-7)u_7(t)+2u_7(t)\]

Answer 11

i think the it should be e^-5s and e^-7s

Answer 12

transform is then\[\large\frac1{s^2}e^{-5s}-\frac 1s2e^{-5s}-\frac1{s^2}e^{-7s}-\frac2se^{-7s}\]yeah exponent is negative, simplify as you see fit

Answer 13

i got 2s instead of 12 s

Answer 14

me too, I think that is right

Answer 15

i got that and it is right

Answer 16

thanks
can i give you some credit too I'm new here

Answer 17

yep that's what I got too
been a while since I've done these
yeah sure, have a medal for being a good sport, welcome to OpenStudy

Answer 18

thanks can i give u a medal?

Answer 19

don't worry about it, I don't go past level 99 ;)

Answer 20

thanks @Euler271

Answer 21

lol thanks again imma close this question :D