1) Упростим выражение:
![\frac{a*(b-3a)^{2} }{3 a^{2} - ab} - 3a= \frac{a*(b-3a)^{2} }{a*(3a-b)} - 3a = \frac{-(3a-b)^{2} }{(3a-b)}](https://tex.z-dn.net/?f=+%5Cfrac%7Ba%2A%28b-3a%29%5E%7B2%7D+%7D%7B3+a%5E%7B2%7D+-+ab%7D+-+3a%3D+%5Cfrac%7Ba%2A%28b-3a%29%5E%7B2%7D+%7D%7Ba%2A%283a-b%29%7D+-+3a+%3D++%5Cfrac%7B-%283a-b%29%5E%7B2%7D+%7D%7B%283a-b%29%7D+)
= -(3a-b) - 3a = -3a+b-3a=-6a+b = b-6a
2) Подставим числовые значения:
а=2,18
b=-5,6
b-6a=-5,6-6*2,18=-5,6-13,08
= -18,68
2) х²+у²+2ху–(х+у)³=(х+у)²–(х+у)³=(х+у)²(1-х-у);
4)(m+2n)³-m²+4n²=(m+2n)²-(m²-4n²)=(m+2n)²-(m-2n)(m+2n)=(m+2n)(m+2n-(m-2n))=(m+2n)(m+2n-m+2n)=(m+2n)•4n;
6)(x+3y)²-x³-9x²y-27xy²-27y³=(x+3y)²-(x+3y)³=(x+3y)²(1-x-3y)
D=a2-a1=1-4=-3
a5=a1+4d=4-3*4=4-12=-8
a10=a1+9d=4-3*9=4-27=-23
S10=(a1+a10)*10/2=(4-23)*5=-19*5=-95