1) (t-8)2 - t(t-6) = (t-8)2 - (t2 - 6t) = t2 - 16t + 64 - t2+6t = 64-10t
при t=-1,5
64-10*(-1,5)=79
2)(3t+2)2 - 4(3t+1) = 9t2 + 12t + 4 - 12t - 4=9t2
при t=-2/3
9*(-2/3)2=9*4/9=4
3)(6t+1)2-(1-6t)2=36t2+12t + 1 - (1-12t+36t2) =36t2 +12t +1-1+12t-36t2=24t
при t=-0,75
24*(-0,75)=-18