Пошаговое объяснение:
var>
lg2
log
2
40
−
log
80
2
log
2
5
=
log
2
10
log
2
2
log
2
40
−
log
2
80
log
2
2
log
2
5
=
log
2
40∗log
2
10−log
2
5∗log
2
80=
log
2
40∗(log
2
2+log
2
5)−log
2
5∗(log
2
2+log
2
40)=
log
2
40∗(1+log
2
5)−log
2
5∗(1+log
2
40)=
log
2
40+log
2
40∗log
2
5−log
2
5−log
2
5∗log
2
40=
log
2
40−log
2
5=log
2
(2
3
∗5)−log
2
5=
log
2
2
3
+log
2
5−log
2
5=log
2
2
3
=3</var>
