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9a^2-6ab+b^2-16
(3-b)^2-16
(3a-b-4)*(3a-b+4)
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2-2sin²x-sinx+1=0
2sin²x+sinx-3=0
sinx=a
2a²+a-3=0
D=1+24=25
a1=(-1-5)/4=-1,5⇒sinx=-1,5∉[-1;1]
a2=(-1+5)/4=1⇒sinx=π/2+2πn
<span>(3 1/4+2 1/6): 2 3\5-2/ :4/9=? </span>