(m-2) x octave-x ^ n-1) + 3x + n is a quartic trinomial about X, and we can find the value of Mn

(m-2) x octave-x ^ n-1) + 3x + n is a quartic trinomial about X, and we can find the value of Mn

m-2=0
m=2
n-1=4
n=5
mn=2x5=10