The Laplace Transform F(x) of a Function F(t) Is Given $F ( x ) = \int _ { 0 } ^ { + \infty } f ( t ) e ^ { - x t } \mathrm {~d} t$

Multiple Choice

The Laplace transform F(x) of a function f(t) is given by the formula. $F ( x ) = \int _ { 0 } ^ { + \infty } f ( t ) e ^ { - x t } \mathrm {~d} t$
Find F(x) if $f ( t ) = e ^ { n t }$ (n constant) .

A) $\frac { 1 } { x }$
B) $\frac { 1 } { x - n }$
C) $\frac { n } { x }$
D) $\frac { n } { x - \mathrm { n } }$
E) $n x - n$