Question

Tìm x không âm biết:
a) 3√x=15
b) -2√x = -10
c) √x > 6
d) √x < 5

Answer 1

a. \(3\sqrt{x}=15\)

<=> \(\sqrt{x}=\dfrac{15}{3}\)

<=> \(\sqrt{x}=5\)

<=> x = \(25\)

b. \(-2\sqrt{x}=-10\)

<=> \(\sqrt{x}=\dfrac{-10}{-2}\)

<=> \(\sqrt{x}=5\)

<=> \(x=25\)

c. \(\sqrt{x}>6\)

<=> \(\left(\sqrt{x}\right)^2>6^2\)

<=> x > 36

d. \(\sqrt{x}< 5\)

<=> \(\left(\sqrt{x}\right)^2=5^2\)

<=> x < 25

Answer 2

a)\(3\sqrt{x}=15\)⇒\(\sqrt{x}=5\)⇒x=25

b)\(-2\sqrt{x}=-10\)⇒\(\sqrt{x}=5\)⇒x=25

c)\(\sqrt{x}>6\)⇒x>36

d)\(\sqrt{x}< 5\)⇒x<25