Question

\(3\sqrt{2x}-5\sqrt{8x}+7\sqrt{18x}=28\)

Answer 1

sorry mìh k bít làm

Answer 2

mình biết lm nhưng k biết gõ dấu căn

Answer 3

\(3\sqrt{2x}-5\sqrt{8x}+7\sqrt{18x}=28\)28

<=> \(3\sqrt{2x}-5.2\sqrt{2x}+7.3\sqrt{2x}=28\)

<=> \(14\sqrt{2x}=28\)

<=> 

Answer 4

mk ấn nhầm giờ mk làm tiếp nha

<=> \(\sqrt{2x}=2\)

<=>  \(2x=4\)

<=> 

Answer 5

CHO MK NHA 

Answer 6

Ta có: \(3\sqrt{2x}-5\sqrt{8x}+7\sqrt{18x}=28\)   \(\left(ĐK:x\ge0\right)\)

    \(\Leftrightarrow3\sqrt{2x}-5\sqrt{4}.\sqrt{2x}+7.\sqrt{9}\sqrt{2x}=28\)

    \(\Leftrightarrow3\sqrt{2x}-10.\sqrt{2x}+21\sqrt{2x}=28\)

    \(\Leftrightarrow4\sqrt{2x}=28\)

    \(\Leftrightarrow\sqrt{2x}=7\)

    \(\Leftrightarrow2x=49\)

    \(\Leftrightarrow x=\frac{49}{2}\)\(\left(TM\right)\)

Vậy \(S=\left\{\frac{49}{2}\right\}\)

Answer 7

\(3\sqrt{2x}-5\sqrt{8x}+7\sqrt{18x}=28\)

ĐKXĐ : x ≥ 0

⇔ \(3\sqrt{2x}-5\sqrt{2^2\cdot2x}+7\sqrt{3^2\cdot2x}=28\)

⇔ \(3\sqrt{2x}-5\cdot\left|2\right|\sqrt{2x}+7\cdot\left|3\right|\sqrt{2x}=28\)

⇔ \(14\sqrt{2x}=28\)

⇔ \(\sqrt{2x}=2\)

⇔ \(2x=4\)

⇔ \(x=2\)( tm )

Vậy x = 2