Áp dụng bđt AM-GM:
\(2x^2+\frac{6}{x^2}+3y^2+\frac{8}{y^2}\)
\(=\left(2x^2+\frac{2}{x^2}\right)+\left(3y^2+\frac{3}{y^2}\right)+\left(\frac{4}{x^2}+\frac{5}{y^2}\right)\)
\(\ge2\sqrt{\frac{4x^2}{x^2}}+2\sqrt{\frac{9y^2}{y^2}}+\left(\frac{4}{x^2}+\frac{5}{y^2}\right)\ge4+6+9=19\)
\("="\Leftrightarrow x=y=\pm1\)
cho cac so thuc x,y thoa man x^2+y^2-xy-9 tim GTNN cua P= x^2+y^2
help meeeeeeee
cho cac so thuc x,y thoa man x^2+y^2-xy-9 tim GTNN cua P= x^2+y^2
help meeeeeeeeeeee
cho hai so duong xy thoa man \(\frac{4}{x^2}+\frac{5}{y^2}\ge9\) tim gia tri nho nhat cua bieu thuc\(Q=2x^2+\frac{6}{x^2}+3y^2+\frac{8}{y^2}\)
cho 2 so x va y thoa man 3x+y=1
a) Tim GTNN cua bt M=3x^2+y^2
b) Tim GTLN cua bt N=x*y
cho x,y thuoc R khac 0 thoa man 2x^2 + y^2/4 +1/x^2 = 4. tim gtnn gtln cua A= 2008+xy
Tim tat cac cac cap so nguyen x,y thoa man a) x^2+5xy+4y^2
b)xy-2x+3y-1
Tim tat cac cac cap so nguyen x,y thoa man a) x^2+5xy+4y^2
b)xy-2x+3y-1
Tim tat cac cac cap so nguyen x,y thoa man a) x^2+5xy+4y^2
b)xy-2x+3y-1
cho 2 số thực duong x y thỏa mãn 4/x^2 +5/y^2>=9 . tim gia tri nho nhat cua bieu thuc Q=2x^2+6/x^2+3y^2+8/y^2
