Đáp án:
Mình làm vậy có gì ko hiểu bạn ns cho mình biết nha!
Mình chuyển dấu nhân thành dấu chấm.
Giải thích các bước giải:
a) (1- 1/9).(1- 1/16).(1- 1/25).(1- 1/36).(1- 1/49)
= (9/9- 1/9).(16/16- 1/16).(25/25- 1/25).(36/36- 1/36).(49/49- 1/49)
= 8/9.15/16.24/25.35/36.48/49
=8.15.24.35.48/9.16.25.36.49
= 2.4.3.5.4.6.5.7.6.8/3.3.4.4.5.5.6.6.7.7
= 2.8/3.7= 16/21;
b) (1- 1/16).(1- 1/25).(1- 1/36).(1- 1/49).(1- 1/64)
= (16/16- 1/16).(25/25- 1/25).(36/36- 1/36).(49/49- 1/49).(64/64- 1/64)
= 15/16.24/25.35/36.48/49.63/64
= 15.24.35.48.63/16.25.36.49.64
= 3.5.4.6.5.7.6.8.7.9/4.4.5.5.6.6.7.7.8.8
=3.9/4.8= 27/48;
c) (1- 1/25).(1- 1/36).(1- 1/49).(1- 1/64).(1- 1/81)
= (25/25- 1/25).(36/36- 1/36).(49/49- 1/49).(64/64- 1/64).(81- 1/81)
= 24/25.35/36.48/49.63/64. 80/81
= 24.35.48.63.80/25.36.49.64.81
= 4.6.5.7.6.8.7.9.8.10/5.5.6.6.7.7.8.8.9.9
= 4.10/5.9= 40/45= 8/9.