A.a)13x+39+21x+63 при x=-3
13x+21x=-39-63
13x+21x=-102
13*(-3)+21*(-3)=-102
-39-63=-102
-102=-102
b)-102=-102
-102+102=0
B.a)121-11x+456-10x при x=11
-11x-10x=-456-121
-11x-10x=-577
-11*11-10*11=-577
-121-110=-577
-231=-577
b)-231=-577
-231+577=346
C)6,3(x+2,4)-9,1(x+1,4) при x=-1,4
6,3x+15,12-9,1x-12,74
6,3x-9,1x=12,74-15,126,3x-9,1x=-2.38
6,3*(-1,4)-9,1*(-1,4)=-2,38
-8,82+12,74=-2,38
3,92=-2,38
3,92+2.38=6.3