1, let f (x) = 0.8 x- 1-lnx.

f( 1/2)= 0.5878 & gt； 0 f( 1)=-0.2 & lt； 0

∴ Within (1/2, 1)

f(3/4)= 0. 1336 & gt； 0

∴ Within (3/4, 1)

f(7/8)= - 0.043840

∴ Within (3/4, 7/8)

So the approximate solution is 0.8.

2. The principle is the same as above. The answer is 2.3.