cho a +2b + 3c >= 14. chứng minh rằng a2 + b2 + c2 >= 14
a+2b+3c>=14. Chứng minh a^2+b^2+c^2>=14. Giúp mình nha
1.cho a < b, chứng minh
3a + 1 < 3b +1
-2a - 5 > - 2b -5
2. chứng minh 4x (-2)+14 > 4x (-1) +14
-3 x2 +5 > -3 x -5+5
3. giải pt
2/3x > -6
-5/6x > 20
3-1/4x >2
5-1/3x >2
Cho a>b>c>0. Chứng minh rằng :
\(a^3b^2+b^3c^2+c^3a^2>a^2b^3+b^2c^3+c^2a^3\)
a) Cho a,b,c>0. chứng minh rằng:\(\frac{a}{3a^2+2b^2+c^2}+\frac{b}{3b^2+2c^2+a^2}+\frac{c}{3c^2+2a^2+b^2}\le\frac{1}{6}\left(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\right)\)
Bài 2: Chứng minh
a, (a+b+c)(a\(^2\)+b\(^2\)+c\(^2\)-ab-ac-bc)= a\(^3\)+b\(^{^{ }3}\)+c\(^3\)-3abc
b, ( 3a+2b-1)(a+5)-2b(a-2)=(3a+5)(a+3)+2(7b-10)
c, 2(a+b+c)(\(\dfrac{b}{2}\)+\(\dfrac{c}{2}\)-\(\dfrac{a}{2}\))=2bc+c\(^2\)+b\(^2\)-a\(^2\)
1.Cho bốn số dương a, b, c, d.
Chứng minh rằng
: \(\sqrt{ab}+\sqrt{cd}< =\sqrt{\left(a+d\right)}\left(b+c\right)\)
2. Cho a2+b2 =<2
Chứng minh rằng:
\(a\sqrt{3a\left(a+2b\right)}+b\sqrt{3b\left(b+2a\right)}=< 6\)
Cho a,b,c>=0. Chứng minh:
\(\frac{a^2}{2b+3c}+\frac{b^2}{2c+3a}+\frac{c^2}{a^2+b^2}\ge\frac{1}{5}\left(a+b+c\right)\)
Cho a+2b+3c >=14 CM a2+b2+c2>=14