Câu hỏi:
Tìm x biết: \(\left( {525 – 725} \right)x = 645 + \left( { – 15 – 30} \right) + 200\)
-
A.
x = -2 -
B.
x = -3 -
C.
x = -4 -
D.
x = -5
Lời giải tham khảo:
Đáp án đúng: C
Ta có:
\(\begin{array}{l}\ \,\left( {525 – 725} \right)x = 645 + \left( { – 15 – 30} \right) + 200\\\,\,\,\,\, – 200x = 645 + \left( { – 45} \right) + 200\\\,\,\,\,\, – 200x = 600 + 200\\\,\,\,\,\, – 200x = 800\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = 800:\left( { – 200} \right)\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = – 4\end{array}\)
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