Sagot :
A= 3/7-2/7 : 8/21=
=3/7-2/7*21/8=
=3/7-42/56=
=24-42/56=
=-18/56=
=-9/28=
B=5²+2²*9=
=(5-2)²*9=
=3²*9=
=9*9=
=81
=3/7-2/7*21/8=
=3/7-42/56=
=24-42/56=
=-18/56=
=-9/28=
B=5²+2²*9=
=(5-2)²*9=
=3²*9=
=9*9=
=81