Эта формула квадрата разности ,которая выражается:
(-7х-1)²=(-7х)²—2×(-7х)×(-1)+(-1)²=49х²-14х+1=7х(7х-2)+1
1) =(x^2-x+6x-6-x^2-x+6x+6)/(x^2-1)=10x/(x^2-1)
2) (3-b)/(b•(b-3))=-1/b
3) (4c^2-1-5c^2+1)/(2c-1)=-c^2/(2c-1)
4)=(2a^2-a^2-3a)/(2a•(a-3)•(a+3))=1/(2a+6)
B2+b3=b1q+b1q^2=b1(q+q^2)=30;
b4-b2=b1q^3-b1q=b1(q^3-q)=90;
(q+q^2)
----------- = 30/90;
(q^3-q)
(1+q)/((q-1)(q+1)) = 1/3;
1/(q-1)=1/3 => q-1=3; q=4.
b1(q+q^2)=30 => b1=30/20=1,5
Ответ: q=4; b1=1,5
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