Question

Tính : 73 - 3|x + 2| = - 47

Answer 1

\(73-3\left|x+2\right|=-47\)

th1: \(x+2\ge0\Leftrightarrow x\ge-2\)

\(\Rightarrow73-3\left|x+2\right|=-47\Leftrightarrow73-3\left(x+2\right)=-47\)

\(\Leftrightarrow73-3x-6=-47\Leftrightarrow-3x=-47-73+6=-114\)

\(\Leftrightarrow x=\dfrac{-114}{-3}=38\left(tmđk\right)\)

th2: \(x+2< 0\Leftrightarrow x< -2\)

\(\Rightarrow73-3\left|x+2\right|=-47\Leftrightarrow73-3\left(-x-2\right)=-47\)

\(\Leftrightarrow73+3x+6=-47\Leftrightarrow3x=-47-73-6=126\)

\(\Leftrightarrow x=\dfrac{126}{3}=-42\left(tmđk\right)\)

vậy \(x=38;x=-42\)

Answer 2

73 - 3|x + 2| = - 47

3|x + 2| = 73 - (- 47)

3|x + 2| = 120

|x + 2| = 120 ÷ 3

|x + 2| = 40

=> x + 2 = 40 ; - 40

Trường hợp 1:

x + 2 = 40

x = 40 - 2

x = 38

Trường hợp 2:

x + 2 = - 40

x = - 40 - 2

x = - 42

Vậy x = 38 ; x = - 42

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