limx→∞(10e3x+8)5/x
⇒limx→∞exp(log((10e3x+8)5/x))
=limx→∞exp[slog(10e3x+8)x]
⇒exp[limx→∞(slog(10e3x+8)x)]
=exp⎡⎢
⎢
⎢
⎢⎣5limx→∞⎛⎜
⎜
⎜
⎜⎝log(10e3x)+log(4e−3x5+1)x⎞⎟
⎟
⎟
⎟⎠⎤⎥
⎥
⎥
⎥⎦
but limx→∞log(4e−3x5+1)=0
⇒exp[5limx→∞(log(10e3x)x)]
Applying L' Hospital's rule
exp⎡⎢
⎢
⎢⎣5limx→0ddxlog(10e3x)dxdx⎤⎥
⎥
⎥⎦
=exp(5limx→∞31)=exp(5×3)=e15.