Đáp án:
Giải thích các bước giải:
13)1/5x(-7/3+2/8):0,25
=1/5x(-56/24+6/24):1/4
=1/5x-25/12:1/4
=-5/12:1/4
=-5/12x4/1
=-5/3
14)1/4-(13/19- -2/8)+(13/19-5/7)
=1/4-(13/19+2/8)+(13/19-5/7)
=1/4-(104/152+38/152)+(91/133-95/133)
=1/4-142/152+-4/133
=38/152-142/152+-4/133
=-104/152+-4/133
=-728/1064+-32/1064
=-760/1064=-5/7
15)9/24+-8/-14-12/32
=9/24+8/14-12/32
=63/168+96/168-12/32
=159/168-12/32
=636/672-252/672
=384/672=4/7
16) I2^2/18+3/9I - 6/27
=I4/18+3/9I - 6/27
=I4/18+6/18I - 6/27
=I5/9I-6/27
5/9-6/27 hay -5/9-6/27
=15/27 -6/27 hay -15/27-6/27
=1/3 hay -7/9
