2.
.......=15m - 12n-12m+8n=3m - 4n
при m= -0,2, n=0,7
3(-0.2) - 4*0.7= - 0.6-2.8= - 3.4
10.
.....=1 2/3 х - 1 2/3*6-5/6*3/5х+5/6*27/10=1 2/3 х - 1/2 х - 10+9/4=1 4/6 х - 3/6 х - 10+2 1/4=1 1/6 х - 7 3/4
при х=27/36
7/6 * 27/36 - 7 3/4=63/72 - 7 54/72= - 6 63/72= - 6 7/8