\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)

Đặt \(S=\frac{1}{\sqrt{a^2-ab+b^2}}+\frac{1}{\sqrt{b^2-bc+c^2}}+\frac{1}{\sqrt{c^2-ca+a^2}}\)

Ta dễ có

\(\sqrt{a^2-ab+b^2}=\sqrt{\frac{1}{4}\left(a+b\right)^2+\frac{3}{4}\left(a-b\right)^2}\ge\frac{1}{2}\left(a+b\right)\)

Sử dụng phép tương tự khi đó:

\(S\le\frac{2}{a+b}+\frac{2}{b+c}+\frac{2}{c+a}\)

\(\le\frac{1}{2}\left(\frac{1}{a}+\frac{1}{b}\right)+\frac{1}{2}\left(\frac{1}{b}+\frac{1}{c}\right)+\frac{1}{2}\left(\frac{1}{c}+\frac{1}{a}\right)\)

\(=3\)

Đẳng thức xảy ra tại a=b=c=1

\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)

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mình cũng đang định hỏi câu đó nè

Khó quá bạn ơi mih cũng ko giải được mih cũng lớp 5 zời ơi sao khó vậy trời nghĩ mãi mà hổng ra hihihi🤣

5,4 : 0,4 x 225 + 4,5 x 775 x 3

=   13,5  x 225  +  3487,5   x 3

=     3037,5       +         10462,5

=               13500

3,024+9,45+25,326

12,474+25,326

37,8

    0,378 : 0,125 + 0,378 : 0,04 + 0,378 x 67

=  0,378 x 8 + 0,378 x 25 + 0,378 x 67

=  0,378 x ( 8 + 25 + 67 )

=  0,378 x 100

=  37,8 

202,8+10,14+152,1+30+20,7

211,94+152,1+30+20,7

365,04+30+20,7

395,04+20,7

415,74

\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)

\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)

Tả mẹ là đề bài dễ tả, bộc lộ nhiều cảm xúc khác nhau đối với mỗi người.

\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)

\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)

\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)

9 hay sao ấy

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