2075:5=(x*75:5)+40

415=(x*15)+40

x*15=415-40

x*15=375

x=375:15

x=25

đáp án x= 25 đó

mình nhanh nhất và đúng luôn nek

415 nhé.ko biết là minnh ánh biết chia ko

\(\left(\frac{1}{3}+\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+\frac{1}{99}\right).y=\frac{2}{3}\)

\(\frac{1}{2}.\left(1-\frac{1}{3}\right)+\frac{1}{2}.\left(\frac{1}{3}-\frac{1}{5}\right)+\frac{1}{2}.\left(\frac{1}{5}-\frac{1}{7}\right)+\frac{1}{2}.\left(\frac{1}{7}-\frac{1}{9}\right)+\frac{1}{2}.\left(\frac{1}{9}-\frac{1}{11}\right).y=\frac{2}{3}\)

\(\frac{1}{2}.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}\right).y=\frac{2}{3}\)

\(\frac{1}{2}.\left(1-\frac{1}{11}\right).y=\frac{2}{3}\)

\(\left(1-\frac{1}{11}\right).y=\frac{4}{3}\)

\(\frac{10}{11}.y=\frac{4}{3}\)

\(\Rightarrow y=\frac{22}{15}\)

\(2.x=\frac{1+2+3+...+9}{1-2+3-4+5-6+7-8+9}+\frac{25.150-60.5+20.75}{1+2+3+...+99}\)

\(2.x=\frac{\left(9+1\right).9:2}{\left(1-2\right)+\left(3-4\right)+\left(5-6\right)+\left(7-8\right)+9}+\frac{2.3.5^2.\left(5^2-2+2.5\right)}{\left(1+99\right).99:2}\)

\(2.x=\frac{45}{\left(-1\right)+\left(-1\right)+\left(-1\right)+\left(-1\right)+9}+\frac{2.3.5^2.33}{100.99.\frac{1}{2}}\)

\(2x=\frac{45}{5}+\frac{50.99}{50.2.99.\frac{1}{2}}=9+\frac{1}{2.\frac{1}{2}}=9+1=10\)

=> 2x = 10

x = 5

a) \(2075:5=\frac{x\times75}{5+40}\)

\(415=\frac{x\times75}{45}\)

\(\Rightarrow x\times75=415\times45\)

\(x\times75=18675\)

\(x=18675:75\)

\(x=249\)

b) \(x+x:5\times7,5+x:2\times9=315\)

\(x+x\times\frac{1}{5}\times7,5+x\times\frac{1}{2}\times9=315\)

\(x\times\left(1+\frac{1}{5}\times7,5+\frac{1}{2}\times9\right)=315\)

\(x\times7=315\)

\(x=315:7\)

\(x=45\)

Lưu ý mình dùng * thay cho dấu nhân và / thay cho dấu chia.

a) 2075/5 = \(\frac{x\cdot75}{5+40}\)

\(\frac{x\cdot75}{5+40}\) = \(\frac{x\cdot75}{45}\) = 415

(x * 75) / 45 = 415

x * 75 = 415 * 45 = 18675

x = 18675 / 75

x = 249

b) x + x / 5 * 7,5 + x / 2 * 9 = 315

x + x * \(\frac{7,5}{5}\)+ x * \(\frac{9}{2}\)= 315

x * 1 + x * \(\frac{7,5}{5}\)+ x * \(\frac{9}{2}\)= 315

x * (1 + \(\frac{7,5}{5}\)+ \(\frac{9}{2}\)) = 315

x * 7 = 315

x = 315 / 7

x = 45

Chúc bạn học tốt !

415 ở đâu vậy

Giải:

\(358.2^3-\dfrac{5^{20}.3^{20}}{15^{18}}+3^2.2075^0\)

\(=358.2^3-\dfrac{5^{20}.3^{20}}{5^{18}.3^{18}}+3^2.1\)

\(=358.2^3-5^2.3^2+3^2\)

\(=358.2^3-3^2\left(5^2+1\right)\)

\(=358.2^3-3^2.26\)

\(=2\left(358.2^2-3^2.13\right)\)

\(=2.1315=2630\)

Vậy ...

(Mình nghĩ có sai sót gì đó, bạn xem lại đề)