Найдите значение выражения: 51/4(12-c)+31/4(-c-8) при c=-0.4
51/4(12-(-0.4))+31/4(-(-0.4)-8)=
=51/4(12+0.4)+31/4(0.4-8)=
=51/4×12.4+31/4×(-7.6)=
=51/4×62/5+31/4×(-38/5)=
=51/2×31/5-31/2×19/5=
=1581/10-589/10=
=496/5=99,2