Question

tìm x biết

a, \(x+\dfrac{1}{5}\ =\dfrac{3}{4}\)

b, \(x+\dfrac{1}{6}+\dfrac{1}{2}=\dfrac{2}{3}\)

c,\(\left(\dfrac{1}{3}\right)^x=\dfrac{1}{729}\)

Answer 1

a) \(x+\dfrac{1}{5}=\dfrac{3}{4}\)

\(x=\dfrac{3}{4}-\dfrac{1}{5}\)

\(x=\dfrac{11}{20}\)

b) \(x+\dfrac{1}{6}+\dfrac{1}{2}=\dfrac{2}{3}\)

\(x+\dfrac{2}{3}=\dfrac{2}{3}\)

\(x=\dfrac{2}{3}-\dfrac{2}{3}\)

\(x=0\)

c) \(\left(\dfrac{1}{3}\right)^x=\dfrac{1}{729}\)

\(x=6\)

Answer 2

a, x+\(\dfrac{1}{5}\)=\(\dfrac{3}{4}\)

x = \(\dfrac{3}{4}\)-\(\dfrac{1}{5}\)

x =\(\dfrac{11}{20}\)

vậy x=\(\dfrac{11}{20}\)

b, x+\(\dfrac{1}{6}+\dfrac{1}{2}=\dfrac{2}{3}\)

x =\(\dfrac{2}{3}-\dfrac{1}{2}-\dfrac{1}{6}\)

x =0

vậy x=0

c,\(\left(\dfrac{1}{3}\right)^x=\dfrac{1}{729}\)

\(\left(\dfrac{1}{3^{ }}\right)^x=\left(\dfrac{1}{3}\right)^6\)

=> x=6

vậy x=6

Answer 3

a, 11/20

b, 0

c,6