\(\dfrac{2}{3}-5x^2=\dfrac{-58}{3}\)

\(\Leftrightarrow5x^2=\dfrac{2}{3}+\dfrac{58}{3}\)

\(\Leftrightarrow5x^2=20\)

\(\Leftrightarrow x^2=4\)

\(\Leftrightarrow x=\pm2\)

\(\dfrac{2}{3}-5x^2=-\dfrac{58}{3}\)

\(5x^2=\dfrac{2}{3}+\dfrac{58}{3}\)

\(5x^2=\dfrac{60}{3}=20\)

\(x^2=\dfrac{20}{5}=4\)

\(x^2=2^2\)

\(x=2\)

Gọi chiều dài nền nhà là x ( m ) ( x ϵ N*  ; x < 48 )

Chiều rộng nền nhà là : \(\dfrac{x}{3}\left(m\right)\)

Theo bài ra , ta có :

 \(x.\dfrac{x}{3}=48\)

\(\Leftrightarrow x^2=24\)

\(\Leftrightarrow x=2\sqrt{6}\)

MÌnh nhầm sửa đoạn cuối nhé : \(x.\dfrac{x}{3}=48\)

\(\Leftrightarrow x^2=144\)

\(\Leftrightarrow x=12\)

x = 2

$3^x+4^x=5^x\iff {\left(\frac{3}{5}\right)}^x+{\left(\frac{4}{5}\right)}^x=1$

TH 1 : x<2 $\Rightarrow {\left(\frac{3}{5}\right)}^x+{\left(\frac{4}{5}\right)}^x>{\left(\frac{3}{5}\right)}^2+{\left(\frac{4}{5}\right)}^2=1$

TH2 : x=2 thỏa

TH3 : x>2

$\Rightarrow {\left(\frac{3}{5}\right)}^x+{\left(\frac{4}{5}\right)}^x<{\left(\frac{3}{5}\right)}^2+{\left(\frac{4}{5}\right)}^2=1$

\(\left(2x-1\right)^2=81\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-1=9\\2x-1=-9\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}2x=10\\2x=-8\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-4\end{matrix}\right.\)

(2x - 1)² = 81

(2x - 1)² = 9²

2x - 1 = 9

2x = 9 + 1

2x = 10

x = 10 : 2

x = 5

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

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=0\end{matrix}\right.\)

(2x-3)² = 9

(2x-3)² = 3²

2x-3=3

2x=3+3

2x=6

x=6:2

x=3

Lời giải:

$(2x-3)^2=49=7^2=(-7)^2$

$\Rightarrow 2x-3=7$ hoặc $2x-3=-7$

$\Rightarrow x=5$ hoặc $x=-2$

(2x-3)²=49
(2x-3)²=7²
2x-3=7
​2x=7+3
2x=10
x=10:2
x=5
NHớ tick mik nha

Lời giải:

Ta có:

\(\frac{4.4^5}{3.3^6}.\frac{6.6^5}{2.2^5}=2^n\)

\(\frac{4^6}{3^7}.\frac{6^6}{2^6}=2^n\)

\(\frac{4^6}{3^7}.(6:2)^6=2^n\)

\(\frac{4^6}{3^7}.3^6=2^n\)

\(\frac{4^6}{3}=2^n\)

\(4^6=3.2^n\) 

Đề có vẻ không đúng lắm. Bạn xem lại

\(\dfrac{4^5+4^5+4^5+4^5}{3^6+3^6+3^6}.\dfrac{6^5+6^5+6^5+6^5+6^5+6^5}{2^5+2^5}\)

\(=\dfrac{4.4^5}{3.3^6}.\dfrac{6.6^5}{2.2^5}=\dfrac{4^6.6^6}{3^7.2^6}=\dfrac{2^{12}.2^6.3^6}{3^7.2^6}=\dfrac{2^{12}}{3}\)

\(\dfrac{1}{2}\)- \(\dfrac{3}{4}\) : ( \(\dfrac{1}{4}\)- \(\dfrac{x}{2}\) ) = \(\dfrac{-3}{8}\)

\(\dfrac{1}{2}\) - \(\dfrac{3}{4}\): \(\dfrac{1-2x}{4}\) = \(\dfrac{-3}{8}\)

       \(\dfrac{3}{4}\) . \(\dfrac{4}{1-2x}\) = \(\dfrac{1}{2}\) - (- \(\dfrac{3}{8}\))

       \(\dfrac{3}{1-2x}\) = \(\dfrac{7}{8}\)

        24 = 7 . (1-2x)

         24 = 7 - 14x

         14 x = 7 - 24

         14x = -17

             x = -17/14

mai mua tất cả  các thứ hết số tiền chưa tính thuế là:

              15 000 + 13 000 + 7 000 = 35 000 (đồng)

thuế vat là : 35 000 x 10 : 100 = 3 500 (đồng)

mai còn lại số tiền là: 50 000 - 35 000 - 3500  = 11500 (đồng)

đs