a) A=2(x+0,25)^2-1,125 \geq -1,125
-> Min A = -1,125 Dấu "=" xảu ra khi x = -0,25
b) B= 3.(x+\frac{1}{3})^2+\frac{14}{3} \geq \frac{14}{3}
Min A = \frac{14}{3} Dấu "=" xảy ra khi x = -\frac{1}{3}
c) C= \frac{1}{2}(y+1)^2+\frac{1}{2} \geq \frac{1}{2}
Min A = \frac{1}{2} Dấu "=" xảy ra khi x = -1...