[Toán 8]: Tìm GTNN và GTLN?

I

iceghost

$1)A=(y+3)^2 + 2(y-1)=y^2+6y+9+2y-2=y^2+8y+16-9=(y+4)^2-9 \ge -9 \\
\implies Min_A = -9 \iff y+4=0 \iff y=-4 \\~\\~\\~\\$
 
F

furelove

$A=-2x^2+3x+1= \frac{13}{4} -2(x^2 - \frac{3}{2}x + \frac{9}{16})
= \frac{13}{4} -2( x- \frac{3}{4})^2 =< \frac{13}{4}$
\Rightarrow max A = 13/4 \Leftrightarrow x= 3/4
 
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