Đáp án D

x + 73 : 5 = 20 + 7 , 5 × 4 x + 73 : 5 = 20 + 30 x + 73 : 5 = 50 x + 73 = 250 x = 250 - 73 x = 177

Vậy x=177

Đáp án cần chọn là: D

a, 45,651 x ( 73 + 20 + 7 ) 

= 45,651 x 100

= 4565,1

b, 35 . 11 . 0,1 + 0,25 . 100 . 0

= 35 . 1,1 + 0

= 38,5 

giúp mình với mình cần gấp ah

a: \(=2.125+5.375+7.15+6.85+7.5\)

=7,5+14+7,5

=15+14=29

b: \(\Leftrightarrow\left(\dfrac{4}{5}\cdot\dfrac{5}{6}+\dfrac{1}{5}\cdot x\right)\cdot30=60\)

=>(2/3+1/5x)=2

=>1/5x=2-2/3=4/3

=>x=4/3*5=20/3

\(a,\frac{x+15}{x}=\frac{4}{3}\Rightarrow4x=3x+45\Leftrightarrow x=45\)

\(b,\frac{7,5-x}{3,5+x}=\frac{5}{6}\Rightarrow17,5+5x=45-6x\Leftrightarrow11x=27,5\Rightarrow x=2,5\)

\(c,\frac{x-20}{x-10}=\frac{x+40}{x+70}\Rightarrow\left(x-20\right)\left(x+70\right)=\left(x-10\right)\left(x+40\right)\)

\(\Leftrightarrow x^2+50x-1400=x^2+30x-400\)

\(\Leftrightarrow20x=1000\)

\(\Rightarrow x=50\)

a. \(\frac{\left(x+15\right)}{x}=\frac{4}{3}\Leftrightarrow4x=3\left(x+15\right)\Leftrightarrow4x=3x+45\Leftrightarrow x=45\)

Vậy x=45

b. \(\frac{7,5-x}{3,5+x}=\frac{5}{6}\Leftrightarrow5\left(3,5+x\right)=6\left(7,5-x\right)\Leftrightarrow17,5+5x=45-6x\Leftrightarrow11x=27,5\Leftrightarrow x=2,5\)

Vậy x=2,5

c. \(\frac{x+20}{x-10}=\frac{x+40}{x+70}\Leftrightarrow\left(x+40\right)\left(x-10\right)=\left(x+20\right)\left(x+70\right)\)

\(\Leftrightarrow x^2+30x-400=x^2+90x+1400\Leftrightarrow-60x=-30\Leftrightarrow x=-30\)

Vậy x=-30

\(a,\left(x+15\right):x=4:3\)

=>\(1+\dfrac{15}{x}=\dfrac{4}{3}\)

=>\(\dfrac{15}{x}=\dfrac{1}{3}\)

=>\(x=3.15=45\)

Vậy x=45

b)\(\dfrac{7,5-x}{3,5+x}=\dfrac{5}{6}\)

\(6\left(7,5-x\right)=5\left(3,5+x\right)\)

=>\(45-6x=17,5+5x\)

=>\(-11x=-27,5\)

=>\(x=2,5\)

Vậy...

c)\(\dfrac{x-20}{x-10}=\dfrac{x+40}{x+70}\)

=>\(\left(x-20\right)\left(x+70\right)=\left(x-10\right)\left(x+40\right)\)

=>\(x^2+50x-140=x^2+30x-40\)

=>\(20x=100\)

=>\(x=50\)

1: Ta có: 7x+6(3-x)=27-20+73

\(\Leftrightarrow7x+18-6x=80\)

\(\Leftrightarrow x=80-18=62\)

Vậy: x=62

2: Ta có: \(6x-5\left(x-7\right)=\left(27-514\right)-486-73\)

\(\Leftrightarrow6x-5x+35=27-514-486-73\)

\(\Leftrightarrow x+35=-1046\)

\(\Leftrightarrow x=-1081\)

Vậy: x=-1081

7,5^x . 5¹⁹ = 5 ²⁰ . 5¹¹

7,5^x . 5¹⁹ = 5³¹

7,5^x =5³¹:5¹⁹

7,5^x=5¹²