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Đặt a/b=c/d=k
=>a=bk; c=dk
\(\dfrac{a^{2022}+b^{2022}}{c^{2022}+d^{2022}}=\dfrac{b^2k^{2022}+b^{2022}}{d^{2022}k^{2022}+d^{2022}}=\left(\dfrac{b}{d}\right)^{2022}\)
\(\dfrac{\left(a+b\right)^{2022}}{\left(c+d\right)^{2022}}=\dfrac{\left(bk+b\right)^{2022}}{\left(dk+d\right)^{2022}}=\left(\dfrac{b}{d}\right)^{2022}\)
=>\(\dfrac{a^{2022}+b^{2022}}{c^{2022}+d^{2022}}=\dfrac{\left(a+b\right)^{2022}}{\left(c+d\right)^{2022}}\)
Lời giải:
$a^{100}+b^{100}=a^{101}+b^{101}=a^{102}+b^{102}$
$\Rightarrow (a^{101}+b^{101})^2=(a^{100}+b^{100})(a^{102}+b^{102})$
$\Rightarrow a^{202}+b^{202}+2a^{101}.b^{101}=a^{202}+b^{202}+a^{100}b^{102}+a^{102}b^{100}$
$\Rightarrow 2a^{101}b^{101}=a^{100}b^{102}+a^{102}b^{100}$
$\Rightarrow a^{100}b^{100}(a^2+b^2-2ab)=0$
$\Rightarrow a^{100}b^{100}(a-b)^2=0$
$\Rightarrow a=0$ hoặc $b=0$ hoặc $a=b$
Nếu $a=0$ thì:
$b^{100}=b^{101}=b^{102}$
$\Rightarrow b^{100}(b-1)=0$
$\Rightarrow b=0$ hoặc b=1$ (đều tm)
$\Rightarrow a^{2022}+b^{2023}=0$ hoặc $1$
Nếu $b=0$ thì tương tự, $a=0$ hoặc $a=1$
$\Rightarrow a^{2022}+b^{2023}=0$ hoặc $1$
Nếu $a=b$ thì thay $a=b$ vào điều kiện đề thì:
$2b^{100}=2b^{101}=2b^{102}$
$\Rightarrow b^{100}=b^{101}=b^{102}$
$\Rightarrow b^{100}(b-1)=0$
$\Rightarrow b=0$ hoặc $b=1$ (đều tm)
Nếu $a=b=0\Rightarrow a^{2022}+b^{2023}=0$
Nếu $a=b=1\Rightarrow a^{2022}+b^{2023}=2$
Vậy $a^{2022}+b^{2023}$ có thể nhận giá trị $0,1,2$
Lời giải:
$b^2=ac\Rightarrow \frac{b}{a}=\frac{c}{b}$
Đặt $\frac{b}{a}=\frac{c}{b}=k\Rightarrow b=ak; c=bk$
Khi đó:
$\frac{a^{2022}+b^{2022}}{b^{2022}+c^{2022}}=\frac{a^{2022}+(ak)^{2022}}{b^{2022}+(bk)^{2022}}$
$=\frac{a^{2022}(1+k^{2022})}{b^{2022}(1+k^{2022})}=\frac{a^{2022}}{b^{2022}} (1)$
Và:
$(\frac{a+b}{b+c})^{2022}=(\frac{a+ak}{b+bk})^{2022}$
$=[\frac{a(k+1)}{b(1+k)}]^{2022}=(\frac{a}{b})^{2022}=\frac{a^{2022}}{b^{2022}}(2)$
Từ $(1); (2)$ ta có đpcm.
a) \(\dfrac{17}{20}< \dfrac{18}{20}< \dfrac{18}{19}\Rightarrow\dfrac{17}{20}< \dfrac{18}{19}\)
b) \(\dfrac{19}{18}>\dfrac{19+2024}{18+2024}=\dfrac{2023}{2022}\Rightarrow\dfrac{19}{18}>\dfrac{2023}{2022}\)
c) \(\dfrac{135}{175}=\dfrac{27}{35}\)
\(\dfrac{13}{17}=\dfrac{26}{34}< \dfrac{26+1}{34+1}=\dfrac{27}{35}\)
\(\Rightarrow\dfrac{13}{17}< \dfrac{135}{175}\)