30x2+30x5+30x3

30x(5+3+2)

30x 10

300

   30 x 2 + 30 x 5 + 30 x 3 

= 30 x ( 2 + 5 + 3 )

= 30 x 10

= 300

30 x 2+ 30 x 5 +30 x3

30x[2+5+3]

30x 10

300

\(\frac{x}{30+3}+\frac{2}{3}=\frac{x}{30-3}\)

\(\Rightarrow\frac{x}{33}+\frac{2}{3}=\frac{x}{27}\)

\(\Rightarrow\frac{x}{33}=\frac{x}{27}-\frac{18}{27}\)

\(\Rightarrow\frac{x}{33}=\frac{x-18}{27}\)

\(\Rightarrow33\left(x-18\right)=27x\)

\(\Rightarrow33x-594=27x\)

\(\Rightarrow594=6x\)

\(\Rightarrow x=99\)

Ta có:

\(\frac{x}{30+3}+\frac{2}{3}=\frac{x}{30-3}\Rightarrow\frac{x}{33}+\frac{2}{3}=\frac{x}{27}\Rightarrow\frac{9x}{297}+\frac{198}{297}=\frac{11x}{297}\Rightarrow9x+198=11x\)

\(\Rightarrow11x-9x=198\Rightarrow2x=198\Rightarrow x=198:2\Rightarrow x=99\)

Vậy x = 99

(2 giờ 30 phút + 3 giờ 15 phút) x 3

= 5 giờ 45 phút x 3

= 15 giờ 135 phút

= 17 giờ 15 phút.

2 giờ 30 phút + 3 giờ 15 phút x 3

= 2 giờ 30 phút + 9 giờ 45 phút

= 11 giờ 75 phút

= 12 giờ 15 phút

\(x^2=900\Leftrightarrow x^2=30^2\Rightarrow x=30\)

Chọn A

mik nghĩ A

Ta có: \(\dfrac{30}{x}-\dfrac{30}{x+3}=\dfrac{1}{2}\)

\(\Leftrightarrow60\left(x+3\right)-60x=x\left(x+3\right)\)

\(\Leftrightarrow x^2+3x-180=0\)

\(\Leftrightarrow x^2+15x-12x-180=0\)

\(\Leftrightarrow\left(x+15\right)\left(x-12\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-15\left(nhận\right)\\x=12\left(nhận\right)\end{matrix}\right.\)

1)x=1;2;3;5;6;10;15;30

2)x=rỗng

3)x=0;7

cứu tui 

Ta có:\(2^{30}=\left(2^3\right)^{10}=8^{10}< 9^{10}=\left(3^2\right)^{10}=3^{20}\)

\(3^{30}=3^{20}.3^{10}< 3^{20}.4^{10}=3^{20}.\left(2^2\right)^{10}=3^{20}.2^{20}=\left(3.2\right)^{20}=6^{20}\)

\(4^{30}=4^{20}.4^{10}=4^{20}.\left(2^2\right)^{10}=4^{20}.2^{20}=\left(4.2\right)^{20}=8^{20}\)

nên \(2^{30}+3^{30}+4^{30}< 3^{20}+6^{20}+8^{20}\)

Ta có : x=2³⁰ + 3³⁰ + 4³⁰

x=2^3.10 + 3^3.10 + 4^3.10

x=(2³)²⁰ + (3³)¹⁰ + (4³)¹⁰

x=8²⁰ + 9¹⁰ + 64¹⁰

y=3²⁰ + 6²⁰ + 8²⁰

y=3^2.10 + 6^2.10 + 8^2.10

y=(3²)¹⁰ + (6²)¹⁰ + (8²)¹⁰

y=9¹⁰ + 36¹⁰ + 64¹⁰

mà 9¹⁰ > 8²⁰ ;36¹⁰ >9¹⁰ ;64¹⁰ = 64¹⁰

nên x<y