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-40x-101=9
-40x-101+101=19+101
-40x=120
x=-3
Ответ:-3
25x²-20x-12=(5x)²-2*5x*2+4-4-12= (5x-2)²-16=(5x-2-4)(5x-2+4)=
= (5x-6)(5x+2)
7,2<a<8.4 2)7.2<a<8.4
1/2.5<1/b<1/2 2/5<1/b<1/2
3) 7.2*2/5<a/b<8.4*1/2
144/50<a/b<4.2
2.88<a/b<4.2