Bài 3: Ghi số tự nhiên

Di Di
1 tháng 10 2023 lúc 10:49

\(a,x^2=64\\ \Rightarrow x^2=8^2\\ \Rightarrow\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right.\)

\(b,\left(x-2\right)^2=16\\ \Rightarrow\left(x-2\right)^2=4^2\\ \Rightarrow\left[{}\begin{matrix}x-2=4\\x-2=-4\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=6\\x=-2\end{matrix}\right.\\ c,\left(2x-3\right)^2=9\\ \Rightarrow\left(2x-3\right)^2=3^2\\ \Rightarrow\left[{}\begin{matrix}2x-3=3\\2x-3=-3\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}2x=6\\2x=0\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=3\\x=0\end{matrix}\right.\)

`g, 2x+5=3^4:3^2`

`=> 2x+5= 3^2`

`=>2x+5=9`

`=> 2x=9-5`

`=>2x=4`

`=>x=4:2`

`=>x=2`

`h, (3x-2^4) .7^3 =2.7^4`

`=> 3x-16 =2. 7^4 : 7^3`

`=> 3x-16 = 2. 7`

`=> 3x-16=14`

`=> 3x=14+16`

`=>3x=30`

`=>x=30:3`

`=>x=10`

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Toru
1 tháng 10 2023 lúc 10:55

\(a,x^2=64\)

\(\Rightarrow x^2=\left(\pm8\right)^2\)

\(\Rightarrow\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right.\)

\(---\)

\(b,\left(x-2\right)^2=16\)

\(\Rightarrow\left(x-2\right)^2=\left(\pm4\right)^2\)

\(\Rightarrow\left[{}\begin{matrix}x-2=4\\x-2=-4\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=6\\x=-2\end{matrix}\right.\)

\(---\)

\(c,\left(2x-3\right)^2=9\)

\(\Rightarrow\left(2x-3\right)^2=\left(\pm3\right)^2\)

\(\Rightarrow\left[{}\begin{matrix}2x-3=3\\2x-3=-3\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}2x=3+3\\2x=-3+3\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}2x=6\\2x=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=6:2=3\\x=0\end{matrix}\right.\)

\(---\)

\(g,2x+5=3^4:3^2\)

\(\Rightarrow2x+5=3^2\)

\(\Rightarrow2x+5=9\)

\(\Rightarrow2x=9-5\)

\(\Rightarrow2x=4\)

\(\Rightarrow x=4:2=2\)

\(---\)

\(h,\left(3x-2^4\right)\cdot7^3=2\cdot7^4\)

\(\Rightarrow3x-2^4=\dfrac{2\cdot7^4}{7^3}\)

\(\Rightarrow3x-16=2\cdot7\)

\(\Rightarrow3x-16=14\)

\(\Rightarrow3x=14+16\)

\(\Rightarrow3x=30\)

\(\Rightarrow x=30:3=10\)

#\(Toru\)

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