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Billy is solving the inequality 4x - 4 > 20:His work is shown:4x - 4 > 20+4+44x > 244 4X < 6Did Billy solve the problem correctly? If not, where did Billy make a mistake

User DaveRandom
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1 Answer

2 votes

4x-4>20

He added 4 to both sides:


\begin{gathered} 4x-4+4>20+4 \\ 4x>24 \end{gathered}

He divided both sides by 4:


\begin{gathered} (4x)/(4)>(24)/(4) \\ x>6 \end{gathered}

However he got:

x < 6

He flipped the inequality sign which is incorrect since he is not dividing by a negative number

User ShreevatsaR
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