\(abcabc+77=213290\)

\(abcabc=213290-77=213213\)

\(\Rightarrow abc=213\)

abcabc= 213290 - 77 = 213213

ai làm nhanh nhất và đung mình sẽ k nha

\(\frac{30\cdot18-30\cdot13}{30\cdot17+90}\)

\(=\frac{30\cdot\left(18-15\right)}{30\cdot17+30\cdot3}\)

\(=\frac{30\cdot3}{30\cdot\left(17+3\right)}\)

\(=\frac{30\cdot3}{30\cdot20}\)

\(=\frac{3}{20}\)

\(\left(x-17\right)-148=0\)

\(x-17=0+148=148\)

\(x=148-17=131\)

Vậy \(x=131\)

(x - 17) - 148 = 0

<=> x - 17 = 148

<=> x = 165

1793.(x : 1972) = 0

<=> x : 1972 = 0

<=> x = 0

\(5^{2019}< 5^{2020}\)

vì 

2020>2019

=>\(5^{2019}< 5^{2020}\)

a) (348 + 6x) = 38 . 12

(348 + 6x) = 456

6x = 456 - 348

6x = 108

x = 108 : 6

x = 18

b) (x-2)^3 + 130 = 194

(x-2)^3 = 64

(x-2)^3 = 8 ^3

<-> x- 2 = 8

x= 8 +2 = 10

c) 681 - 3^x +1 = 24 . 25

681 - 3^x + 1 = 600

3^x +1 = 681 - 600

3^x +1 = 81

3^x = 81 -1

3^ x = 80

-> x thuộc rỗng 

d) 549 : 9 . x - 84 + 16 = 1701

61 . x - 84 = 1701 - 16

61 . x - 84 = 1685

61.x = 1685 + 84

61 . x = 1769

x = 1769 : 61

x = 29

Đúng giúp mk nhé!

\(\frac{2-7x}{4+21x}=\frac{5-x}{7+3x}\)

\(\Rightarrow\left(2-7x\right)\left(7+3x\right)=\left(4+21x\right)\left(5-x\right)\)

\(\Rightarrow14+6x-49x-21x^2=20-4x+105x-21x^2\)

\(\Rightarrow6x-49x-21x^2+4x-105x+21x^2=20-14\)

\(\Rightarrow-144x=6\)

\(\Rightarrow x=\frac{-1}{24}\)