-12;-24;-48 b1=-12 q=-24/-12=2
s7=b1*(q⁷-1)/(q-1)=-12*127=-1524
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s6? -3;6;-12 b1=-3 q=6/-3=-2
s6=-3((-2)⁶-1)/(-2-1)=-3*63/-3=63
25xˇ2-4 -(25xˇ2-10x+1)=4
10x-1=4,10x=5, x=1/2
100xˇ2-16 =( 10x)ˇ2 - 4ˇ2 = (10x+4)(10x-4)=4.(5x+2)(5x-2)
7)1/81aˇ2-0,09cˇ4 = (1/9.a)ˇ2 - (0,3cˇ2)ˇ2=(1/9a +0,3cˇ2)(1/9-0,3cˇ2)
(b+8)ˇ2-4bˇ2 = (b+8)ˇ2 - (2b)ˇ2= (b+8+2b)(b+8-2b)=
=((3b+8)(8-b)
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