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a) 4.25-12.5+170:10

=100-60+17

=40+17

=57

b) (7+33:32).4-3

=(7+3).4-3

=10.4-3

=40-3

=37

c) 12:{400:[500-(125+25.7)]}

=12:{400:[500-(125+175)]}

=12:{400:[500-300]}

=12:{400:200}

=12:2

=6

d) 168+{[2.(24+32)-2560]:72}

=168+{[2.(16+9)-1]:49}

=168+{[2.25-1]:49}

=168+{[50-1]:49}

=168+{49:49}

=168+1

=169

6 tháng 9 2019

a) \(5^x-\left(5^3\right)^2=625\)

\(\Leftrightarrow5^x-5^6=5^4\)

\(\Leftrightarrow x-6=4\)

\(\Leftrightarrow x=10\)

b) \(\left(\frac{12}{25}\right)^x=\left(\frac{5}{3}\right)^{-2}-\left(-\frac{3}{5}\right)^4\)

4 tháng 9 2020

\(\left(\frac{12}{25}\right)^x=\left(\frac{5}{3}\right)^{-2}-\left(-\frac{3}{5}\right)^4\)

=> \(\left(\frac{12}{25}\right)^x=\frac{9}{25}-\frac{81}{625}\)

=> \(\left(\frac{12}{25}\right)^x=\frac{225}{625}-\frac{81}{625}=\frac{144}{625}\)

=> \(\left(\frac{12}{25}\right)^x=\left(\frac{12}{25}\right)^2\)

Vậy x = 2

4 tháng 9 2020

                 Bài làm :

Ta có :

\(\left(\frac{12}{25}\right)^x=\left(\frac{5}{3}\right)^{-2}-\left(-\frac{3}{5}\right)^4\)

 \(\Leftrightarrow\left(\frac{12}{25}\right)^x=\frac{9}{25}-\frac{81}{625}\)

 \(\Leftrightarrow\left(\frac{12}{25}\right)^x=\frac{225}{625}-\frac{81}{625}=\frac{144}{625}\)

 \(\Leftrightarrow\left(\frac{12}{25}\right)^x=\left(\frac{12}{25}\right)^2\)

\(\Leftrightarrow x=2\)

Vậy x=2

24 tháng 8 2019

a)\(\left(5x+1\right)^2=\frac{36}{49}\\ \left(5x+1\right)^2=\left(\frac{6}{7}\right)^2\\ \Rightarrow\left[{}\begin{matrix}5x+1=\frac{6}{7}\\5x+1=\frac{-6}{7}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{-1}{35}\\x=\frac{-13}{35}\end{matrix}\right.\)

vậy...

24 tháng 8 2019

2.

a) \(\left(5x+1\right)^2=\frac{36}{49}\)

\(5x+1=\pm\frac{6}{7}\)

\(\left[{}\begin{matrix}5x+1=\frac{6}{7}\\5x+1=-\frac{6}{7}\end{matrix}\right.\)\(\left[{}\begin{matrix}5x=\frac{6}{7}-1=-\frac{1}{7}\\5x=\left(-\frac{6}{7}\right)-1=-\frac{13}{7}\end{matrix}\right.\)\(\left[{}\begin{matrix}x=\left(-\frac{1}{7}\right):5\\x=\left(-\frac{13}{7}\right):5\end{matrix}\right.\)

\(\left[{}\begin{matrix}x=-\frac{1}{35}\\x=-\frac{13}{35}\end{matrix}\right.\)

Vậy \(x\in\left\{-\frac{1}{35};-\frac{13}{35}\right\}.\)

Chúc bạn học tốt!

`@` `\text {Ans}`

`\downarrow`

`(-12/25 x^4 y^3 z^5) \div 4/5 x^4 yz^2`

`= (-12/25 \div 4/5)*(x^4 \div x^4) * (y^3 \div y) * (z^5 \div z^2)`

`= -3/5y^2z^3`

14 tháng 7 2023

\(\dfrac{\left(-\dfrac{12}{25}x^4y^3z^5\right)}{\dfrac{4}{5}x^4y^2}=\left(-\dfrac{12}{25}\div\dfrac{4}{5}\right)\left(x^4\div x^4\right)\left(y^3\div y\right)\left(z^5\div z^2\right)\)

\(=-\dfrac{3}{5}y^2z^3\)

17 tháng 7 2019

1) \(\frac{25}{12}.x+\frac{11}{15}=\frac{9}{10}\)

=> \(\frac{25}{12}.x=\frac{9}{10}-\frac{11}{15}\)

=> \(\frac{25}{12}.x=\frac{1}{6}\)

=> \(x=\frac{1}{6}:\frac{25}{12}\)

=> \(x=\frac{2}{25}\)

Vậy \(x=\frac{2}{25}\).

3) \(\frac{29}{12}.\left[x\right]-\frac{5}{6}=\frac{3}{8}\)

=> \(\frac{29}{12}.\left[x\right]=\frac{3}{8}+\frac{5}{6}\)

=> \(\frac{29}{12}.x=\frac{29}{24}\)

=> \(x=\frac{29}{24}:\frac{29}{12}\)

=> \(x=\frac{1}{2}\)

Vậy \(x=\frac{1}{2}\).

4) \(\left[4x+\frac{3}{4}\right]-\frac{5}{4}=2\)

=> \(\left[4x+\frac{3}{4}\right]=2+\frac{5}{4}\)

=> \(4x+\frac{3}{4}=\frac{13}{4}\)

=> \(4x=\frac{13}{4}-\frac{3}{4}\)

=> \(4x=\frac{5}{2}\)

=> \(x=\frac{5}{2}:4\)

=> \(x=\frac{5}{8}\)

Vậy \(x=\frac{5}{8}\).

5) 2x + 2x+3 = 144

⇔ 2x + 2x . 23 = 144

⇔ 2x . (1 + 23) = 144

⇔ 2x . 9 = 144

⇔ 2x = 144 : 9

⇔ 2x = 16

⇔ 2x = 24

=> x = 4

Vậy x = 4.

Chúc bạn học tốt!