1)b5=28,b6=-4
b6=b5×q
-4=28×q
q=-1/7
2)b1=1/16,q=-2
b4=b1×q³=1/16×(-2)³=-1/2
3)b5=25,b6=125
125=25×q
q=5
b6=b1×q^5
125=b1×5^5
b1=1/25
b2=b1×q=1/25×5=1/5
4)b1=5,b4=135
b4=b1×q³
135=5×q³
q=3
S4=b1-b4q/1-q=5-135×3/-2=200
5)—
6) 0,2111
10x=2,111
100x=21,11
100x-10x=21-2=19
90x=19
x=19/90
1)b5=28,b6=-4
b6=b5×q
-4=28×q
q=-1/7
2)b1=1/16,q=-2
b4=b1×q³=1/16×(-2)³=-1/2
3)b5=25,b6=125
b6=b5×q
125=25×q
q=5
b6=b1×q^5
125=b1×5^5
b1=1/25
b2=b1×q=1/25×5=1/5
4)b1=5,b4=135
b4=b1×q³
135=5×q³
q=3
S4=b1-b4q/1-q=5-135×3/-2=200
5)—
6) 0,2111
10x=2,111
100x=21,11
100x-10x=21-2=19
90x=19
x=19/90