Question

1) 0.2*(2.1x-2.3y)-0.4*(3.1y+1.9x)  2)-4*(8x-9y)+3*(6x-4y) если х=-2,8 , у=0,9

Answer 1

1) 0.2*(2.1x-2.3y)-0.4*(3.1y+1.9x)=0,42х-0,46у-1,24у-0,76х=-0,34х-1,7у=-1,7*(0,2х+у)

 

 

 2)-4*(8x-9y)+3*(6x-4y)=-32х+36у+18х-12у=-14х+24у=2*(-7х+12у)=2*((-7)*(-2,8)+12*0,9)=

=2*(19,6+10,8)=60,8