Question

Решите пж 1,2,3Дам 50 баллов!!!!♥️

Answer 1

Ответ:

1) -106,5

2) $-\frac{19}{6}$

3) -17,7

Пошаговое объяснение:

1) 6b-7(12-3b)=6b-84+21b=27b-84=

при b=-5/6

=-135/6-84=-106,5

2)

$\frac{15}{16} (5\frac{1}{3}x-\frac{4}{15}y)-\frac{7}{23}(3\frac{2}{7}x-2\frac{4}{21}y)$

x=-1, y=2.

$=\frac{15}{16} (\frac{16}{3}x-\frac{4}{15}y)-\frac{7}{23}(\frac{23}{7}x-\frac{46}{21}y)=\\=(\frac{15}{3}x-\frac{4}{16}y)-x+\frac{46*7}{21*23}y=\\=5x-\frac{1}{4}y-x+\frac{2}{3}y=\\=4x+y(\frac{2}{3}-\frac{1}{4})=\\=4x+y(\frac{8-3}{12})=\\=4x+\frac{5}{12}y=$

при х=-1, у=2

$=4(-1)+\frac{5}{12}*2=-4+\frac{5}{6}=\frac{5}{6}-4=\frac{5-24}{6} =-\frac{19}{6}$

3)

$6\frac{5}{9}(n-9)+2\frac{2}{9} (18-n)=\\\frac{59}{9}(n-9)+\frac{20}{9} (18-n)=\\\frac{59n}{9}-59+\frac{20*18}{9}-\frac{20n}{9}=\\\frac{59n-20n}{9}-59+40=\\\frac{39n}{9}-19=$

при n=0,3

$\frac{39*0,3}{9}-19=1,3-19=-17,7$