(15m+? )^2=225m^2+12n^3m+0,16n^6 найдите "? "

(a+b)²=a²+2×a×b+b².(15m+?)²=225m²+2×15m×?+0,16n^6=(15m+0,4n³)

2×15m×?=12n³m
30m×?=12n³m
?=(12n³m)/30m
?=12n³/30
?=0,4n³

?²=(0,16n^6)=(0,4n³)²
?=0,4n³