19/(x²+x-12)≥0
x²+x-12=0⇒x1+x2=-1 U x1*x2=-12⇒x1=-4 U x2=3
+ _ +
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-4 3
x∈(-≈;-4) U (3;≈)
2x²-5x=2x-5
2x²-7x+5=0
D=49-40=9
x1=(7-3)/4=1⇒y1=2*1-5=-3
x2=(7+3)/4=2,5⇒y2=2*2,5-5=0
(1;-3) U (2,5;0)
2x²+7x-4=x²-16 x≠-4 U x≠=4
x²+7x+12=0
x1+x2=-7 U x1*x2=12
x1=-4-не удов усл
x2=-3