2x^2 - 20x + 18 = 0 // : 2
x^2 - 10x + 9 = 0
D = 100 - 36 = 64 = 8^2
x1 = ( 10 + 8)/2 = 18/2 = 9;
x2 = ( 10 - 8)/2 = 2/2 = 1;
A1=6,d=4
a11=a1+10d
a11=6+10*4
a11=46
Y=6-x² , y = -x
6-x²=-x
x²-x-6=0
(x-3)(x+2)=0
a)x-3=0, x=3 , B(3,-3)
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b)x+2=0, x=-2, A(-2,2)
(5у+5)*(3у-5)=15у^2-25у+15у-25=15у^2-10у-25