D = -15 + 19 = 4
<span>a81 = -19 + 80*4 = 320 - 19 = 301
</span>
<span>600-2p=300+4p
600-2р-300-4р=0
300-6р=0
6р=300
р=50</span>
(10a+b)(10a+c)= 100a^2 + 10ac + 10ab + bc = 100a^2 + 10a(b+c) +bc=
100a^2 +100a +bc = 100a (a+1) +bc.
а) 32*38 = (10*3 +2)(10*3 + 8) = 100*3(3+1) +2*8 = 1200+16 = 1216
и остальное по подобию