|R|=20cm=0,2m
y2=y1;
x1+x2=80
—————————
a)x2=?
x2/x1=y2/y1
=>x2/x1=3y1/y1
=>x2=3x1
=>x1+3x1=80 cm
=>x1=20cm=0,2m
=>x2=80-20=60cm=0,6m
b)1/f=1/x2-1/x1
=> 1/f=1/0,6-1/0,2
=>1/f=10/6-10/2
=>1/f=-20/6
=>f=-6/20
=-0,3 m
c)1/f=(n-1)*2/|R|
=>-1/0,3=(n-1)*2/0,2
=>-3,3=10n-10
=>10n= 6,7
=>n=0,67
7.f=7,5cm=0,075m
R=4,5 cm= 0,045m
——————————-
a)n=?
1/f=(n-1)*2/R
1/0,075=(n-1)*2/0,045
1000/75=(n-1)*2000/45
13,3=(n-1)*44,4
=>n-1=0,3
=>n=0,4
b)y2=y1/3,x1=?
=>y1=3y2
=>y2/y1=x2/x1
=>y2/3y2=x2/x1
=>x2/x1=1/3
=>x1=3x2
1/f=1/x2-1/x1
1/0,075=1/x2-1/3x2
=>1000/75=2/3x2
13,3=2/3x2
=>3x2=x1=2/13,3=0,15 m
c)C=?, na=4/3
C=(na-1)*2/R
C=(3/4-1)*2/0,045
C=-1/4*2000/45
=>C=-500/45=-11,11
