Question

Tìm x bt

a) (x-5) + (x-7) = -12

b) 3x - 44 = -109 -2x

c) 2 ( x-5) - 5 (3+x) =-109

d) (x-3) . (x+5 ) < 0

Answer 1

\(a.\)

\(\Leftrightarrow x-5+x-7=-12.\)

\(\Leftrightarrow x=-12+-12\)

\(\Leftrightarrow x=-24\)

\(b.\)

\(\Leftrightarrow3x+2x=-109+44\)

\(\Leftrightarrow5x=-65\)

\(\Rightarrow x=-13\)

\(c.\)

\(\Leftrightarrow2x-10-15+5x=-109\)

\(\Leftrightarrow2x-5x=-109+15+10\)

\(\Leftrightarrow3x=-84\)

\(\Rightarrow x=-28\)

\(d.\)

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Answer 2

d) \(\left(x-3\right)\left(x+5\right)< 0\)

\(\Leftrightarrow\orbr{\begin{cases}x-3< 0\\x+5< 0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x< 3\\x< -5\end{cases}}\)