(cos7a+cosa)/(sin7a-sina)=2cos4acos3a/2sin3acos4a=cos3a/sin3a=ctg3a
<span>Log3 (2x-5)+log3 (2x-3)=log3(3)
(2x-5)(2x-3)=3
4x^2+15-16x=3
4x^2-16x+12=0
x=[8+-sqrt(64-48)]/4=[8+-4]/4
x=1
x=3
2x-5>= x>2,5
оответ х=3
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2) <span>5/16;5/8;5/4;5/2
2*2=4
2*4=8
8*2=16
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