-18х² + 36ху - 18у² = - 18(х² - 2ху + у²) = -18(х-у)² = - 18(х-у)(х-у)
1) q=2
S7=635
Sn=b1(q^7-1)/(q-1)
b1(2^7-1)/(2-1)=635
b1=635/127=5
bn=b1q^(n-1)
b6=5*2^5=5*32=160
2) a={1-x;-1-y;2-z}
1-x=2 x=-1
-1-y=-3 y=2
2-z=-1 z=3
координаты начала вектора (-1;2;3)
1)(x+11-x)(x+11+x)=11
11(2x+11)=11
2x= -10
x= -5
2)44+z^2-144-24z-z^2=0
-100-24z=0
z= -25/6
3)69-169+26y-y^2+y^2=0
-100+26y=0
y=50/13
4)31-t^2=-t^2+18t-81
31-t^2+t^2-18t+81=0
112=18t
t=56/9
( X + 7 )^2 = 28X
X^2 + 14X + 49 = 28X
X^2 - 14X + 49 = 0
D = 196 - 196 = 0
X = 14 : 2 = 7
Ответ Х = 7
В)
(p-q)²-2(p²-q²)+(p+q)²
p²-2pq+q²-2p²+2q²+p²+2pq+q²
4q²
г)
(x+2y)²+2(x²-4y²)+(2y-x)²
x²+4xy+4y²+2x²-8y²+4y²-4xy+x²
4x²