(a) 5 sinh x + cosh x
=5.2ex−e−x+2ex+e−x
=25ex−25e−x+21ex+21e−x=26ex+2−4e−x
A=3,B=−2
(b) 5 sinh x + cosh x + 5 = 0
=5.2ex−e−x+2ex+e−x+5=0
let ex = t
than
25(t−t1)+21(t+t1)+5=0
⟹3t2+5t−2=0
t=6−5±49
ex=6−5+7 ∵ex>0 (always)
x=ln(31)
here a=31
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