Tìm x, biết:
a) \({1 \over 3} + x = {3 \over 4}\) b) \( – {2 \over 5} – x = {{ – 3} \over 8}\)
c) \(x – {2 \over 3} = – {3 \over 4}\) d) \( – {4 \over 5} – {1 \over 2} = – x\)
e) \({3 \over 2}x – {4 \over 5} = {1 \over 2}x\)
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\(\eqalign{ & a){1 \over 3} + x = {3 \over 4} \cr & x = {3 \over 4} – {1 \over 3} \cr & x = {9 \over {12}} – {4 \over {12}} \cr & x = {5 \over {12}} \cr & b) – {2 \over 5} – x = {{ – 3} \over 8} \cr & {{ – 2} \over 5} + {3 \over 8} = x \cr & {{ – 16} \over {40}} + {{15} \over {40}} = x \cr & x = – {1 \over {40}} \cr & c)x – {2 \over 3} = – {3 \over 4} \cr & x = {{ – 3} \over 4} + {2 \over 3} \cr & x = {{ – 9} \over {12}} + {8 \over {12}} \cr & x = {{ – 1} \over {12}} \cr & d) – {4 \over 5} – {1 \over 2} = – x \cr & x = {4 \over 5} + {1 \over 2} \cr & x = {8 \over {10}} + {5 \over {10}} \cr & x = {{13} \over {10}} = 1{3 \over {10}} \cr & e){3 \over 2}x – {4 \over 5} = {1 \over 2}x \cr & {3 \over 2}x – {1 \over 2}x = {4 \over 5} \cr & \left( {{3 \over 2} – {1 \over 2}} \right)x = {4 \over 5} \cr & x = {4 \over 5} \cr} \)