121-\(12\left(x-1\right)^3=25\)

\(12\left(x-1\right)^3=121-25=96\)

\(\left(x-1\right)^3=8\)

\(x-1=2\)

\(x=3\)

\(121-12(x-1)^3=25\\\Rightarrow 12(x-1)^3=121-25\\\Rightarrow12(x-1)^3=96\\\Rightarrow(x-1)^3=96:12\\\Rightarrow(x-1)^3=8\\\Rightarrow(x-1)^3=2^3\\\Rightarrow x-1=2\\\Rightarrow x=2+1\\\Rightarrow x=3\\Vậy:x=3\)

a, để A<1\(\Rightarrow\dfrac{x-2}{x+3}< 1\Rightarrow x-2< x+3\Rightarrow-5< 0\left(luôn.đúng\right)\)

Vậy x∈R

=>3x+20=50

hay x=10

=>3x+20=50

hay x=10

x+x+x+20      =25x2

x+x+x+20      =50

x+x+x            = 50-20

x+x+x            =30

Vậy x=10 vì 10+10+10=30

\(\Leftrightarrow3x+10=25\\ \Leftrightarrow3x=25-10=15\\ \Leftrightarrow x=\dfrac{15}{3}=5\)

=>3x=15

hay x=5

\(\Leftrightarrow 3x + 10 = 25\)

\(\Leftrightarrow 3x = 25 - 10 = 15\)

\(\Leftrightarrow x = \dfrac{15}{3^0} = 5\)

số 0 ko liên quan nhé!

help

Vì 4x=5y$\Rightarrow \frac{x}{5}=\frac{y}{4}$

      Áp dụng tính chất dãy tỉ số bằng nhau ta có:

$\Rightarrow \frac{x}{5}=\frac{y}{4}=\frac{x+y}{5+4}=\frac{90}{9}=10$

$\Rightarrow \{\begin{array}{c}\frac{x}{5}=10\\ \frac{y}{4}=10\end{array}$$\Rightarrow \{\begin{array}{c}x=50\\ y=40\end{array}$

Vậy x=50;y=40

Ta có: 4x=5y

nên \(\dfrac{x}{5}=\dfrac{y}{4}\)

hay \(\dfrac{x}{35}=\dfrac{y}{28}\left(1\right)\)

Ta có: 3y=7z

nên \(\dfrac{y}{7}=\dfrac{z}{3}\)

hay \(\dfrac{y}{28}=\dfrac{z}{12}\left(2\right)\)

Từ \(\left(1\right),\left(2\right)\) suy ra \(\dfrac{x}{35}=\dfrac{y}{28}=\dfrac{z}{12}\)

hay \(\dfrac{x}{35}=\dfrac{3y}{84}=\dfrac{2z}{24}\)

Áp dụng tính chất của dãy tỉ số bằng nhau, ta được: 

\(\dfrac{x}{35}=\dfrac{3y}{84}=\dfrac{2z}{24}=\dfrac{x-3y+2z}{35-84+24}=\dfrac{-25}{-25}=1\)

Do đó: x=35; y=28; z=12

=2x2/1x3 x 3x3/2x4x4/3x5 x ... x 11x11/10x12

=2x2x3x3x4x4x...x11x11/1x3x2x4x3x5x...x10x12

= 2x3x4x...x11)x(2x3x4x...x11)/(1x2x3x4x...x11)/(1x2x3x...x10)x(2x3x4x...x11)

=11x2/1x12

=22/12

=11/6

4/3x9/8x16/15x...x121/120=\(\dfrac{2^2}{1\cdot3}\)x\(\dfrac{3^2}{2\cdot4}\)x\(\dfrac{4^2}{3\cdot5}\)x...x\(\dfrac{11^2}{10\cdot12}\)=\(\dfrac{2}{3}\)x\(\dfrac{11}{10}\)=\(\dfrac{11}{15}\)

4/3x9/8x16/15x...x121/120=\(\dfrac{2^2}{1\cdot3}\)x\(\dfrac{3^2}{2\cdot4}\)x...x\(\dfrac{11^2}{10\cdot12}\)=\(\dfrac{2}{3}\)x\(\dfrac{11}{10}\)=\(\dfrac{11}{15}\)

\(\dfrac{10.4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}=\dfrac{5.2.2^{12}.3^{10}+3^9.2^9.2^3.3.5}{2^{12}.3^{12}-2^{11}.3^{11}}\)

\(=\dfrac{5.2^{13}.3^{10}+2^{12}.3^{10}.5}{2^{11}.3^{11}\left(2.3-1\right)}=\dfrac{2^{12}.3^{10}.5\left(2+1\right)}{2^{11}.3^{11}.5}\)

\(=\dfrac{2^{11}.2.3^{10}.5.3}{2^{11}.3^{10}.3.5}=2\)

`@` `\text {Ans}`

`\downarrow`

`a,`

`(x-1954) \times 5=50`

`x-1954 = 50 \div 5`

`x-1954 = 10`

`x=10 + 1954`

`x= 1964`

`B.`

`48 - 40 \times x=8`

`40 \times x=48-8`

`40 \times x = 40`

` x=40 \div 40`

`x=1`

`C.`

`2+70 \div x = 3`

`70 \div x = 3-2`

`70 \div x = 1`

`x=70 \div 1`

`x=70`

`D. [3 \times (x+2) \div 7]  \times  4=120`

`3 \times (x+2) \div 7 = 120 \div 4`

`3 \times (x+2) \div 7 =30`

`3 \times (x+2) = 30 \times 7`

`3 \times (x+2)=210`

`x+2=210 \div 3`

`x+2=70`

`x=70-2`

`x=68`

`E.`

`7,2 \div [ (0,6 \times x+8) \div 20 + 59] = 0,12?` Thiếu ngoặc bạn nhé._.

\(a,\left(x-1954\right)\times5=50\\ x-1954=50:5\\ x-1954=10\\ x=1954+10\\ x=1964\\b.48-40\times x=8\\40\times x=48-8\\40\times x=40\\ x=40:40\\ x=1 \\ c.2+70:X=3\\ 70:x=3-2\\ 70:x=1\\ x=70:1\\ x=70\\ d,\left[3\times\left(x+2\right):7\right]\times4=120\\ 3\times\left(x+2\right):7-120:4\\ 3\times\left(x+2\right):7=30\\ \left(x+2\right):7=30:3\\ \left(x+2\right):7=10\\ x+2=10\times7\\ x+2=70\\ x=70-2\\ x=68\)