1
|2x-1|=4x+7
1)x<1/2<br>2x-1=-4x-7
6x=-6
x=-1
2)x≥1/2
2x-1=4x=7
2x=-8
x=-4 не удов усл
ответ х=-1
2
3x+4≤x²≤9
{x²≥3x+4⇒x²-3x-4≥0 x1+x2=3 U x1*x2=-4 x1=-1 U x2=4⇒x≤-1 U x≥4
{x²≤9⇒(x-3)(x+3)≤0 x=3 x=-3⇒-3≤x≤3
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x∈[-3;-1]