Ta có:

\(x^2+\dfrac{1}{x^2}=4\)\(\left(x\ne0\right)\)

\(\left(x^2+\dfrac{1}{x^2}\right)^2=16\)

\(x^4+\dfrac{2.x^2}{x^2}+\dfrac{1}{x^4}=16\)

\(x^4+\dfrac{1}{x^4}=16-2=14\)

x² + 1/x² = 4

⇒ (x² + 1/x²)² = 16

⇒ x⁴ + 2.x².1/x² + 1/x⁴ = 16

⇒ x⁴ + 1/x⁴ + 2 = 16

⇒ x⁴ + 1/x⁴ = 16 - 2

⇒ x⁴ + 1/x⁴ = 14

`@TH1: x < 1`

Ta có: `Bth=1-x+3-x+5-x+7-x=16-4x`

`@TH2: 1 <= x < 3`

Ta có: `Bth=x-1+3-x+5-x+7-x=14-2x`

`@TH3: 3 <= x <= 5`

Ta có: `Bth=x-1+x-3+5-x+7-x=8`

`@TH4: 5 < x <= 7`

Ta có: `Bth=x-1+x-3+x-5+7-x=2x-2`

`@TH5: x > 7`

Ta có: `Bth=x-1+x-3+x-5+x-7=4x-16`

mong các bạn giải giúp mình

Ta có:

\(\widehat{xOn}=180^o-\widehat{nOy}=180^o-30^o=150^o\)

\(\widehat{xOm}=\widehat{nOy}=30^o\)(đối đỉnh)

\(\widehat{mOy}=\widehat{xOn}=150^o\)(đối đỉnh)

3 I don't have a ladder

4 We didn't have enough time

5 He didn't have a map

6 She doesn't have any money

7 I don't have enough energy

8 They didn't have a camera

donate: book, fresh water, old clothes, water, food, money

clean: shool yard, houses, parks, streets, buildings

help: elderly people, homeless people, street children, poor people

repair: houses, streets, schoolyard, buildings

\(9:27^x=\dfrac{1}{18}\)

\(\Rightarrow9:\left(3^3\right)^x=\dfrac{1}{18}\)

\(\Rightarrow3^{3x}=9:\dfrac{1}{18}\)

\(\Rightarrow3^{3x}=162\)

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