Đáp án:a)$x=\frac{-3}{4}$
b)$x=\frac{11}{20};\frac{-19}{20}$
Giải thích các bước giải:
a)$(3\tfrac{1}{2}+2x)·2\tfrac{2}{3}=5\tfrac{1}{3}$
⇒$(\frac{7}{2}+2x)·\frac{8}{3}=\frac{16}{3}$
⇒$\frac{7}{2}+2x=2⇒ 2x=\frac{-3}{2}$
⇒ $x=\frac{-3}{4}$
b)$|x+\frac{1}{5}|=\frac{3}{4}$
Nếu x>0 thì $x+\frac{1}{5}=\frac{3}{4}⇒ x=\frac{3}{4}-\frac{1}{5}=\frac{11}{20}$
Nếu x<0 thì $x+\frac{1}{5}=-\frac{3}{4}⇒ x=-\frac{3}{4}-\frac{1}{5}=\frac{-19}{20}$
a. ((3$\frac{1}{2}$ + 2x) . 2$\frac{2}{3}$ = 5$\frac{1}{3}$ = ($\frac{7}{2}$ + 2x) . 2 . $\frac{2}{3}$ = $\frac{16}{3}$
= ($\frac{7}{2}$ + 2x) . $\frac{4}{3}$ = $\frac{16}{3}$
= $\frac{14}{3}$ + $\frac{8}{3}$x = $\frac{16}{3}$
= 14 + 8x = 16
= 8x = 16 - 14
= 8x = 2 = x
= $\frac{1}{4}$
Vậy. ......................
b. |x + $\frac{1}{5}$ = $\frac{3}{4}$
= $\left \{ {{x + \frac{1}{5} = \frac{3}{4} } \atop {x + \frac{1}{5} =-\frac{3}{4} }} \right.$
= $\left \{ {{x = \frac{11}{20} } \atop {x = -\frac{19}{20} }} \right.$
Vậy x = ......... hoặc .........
Để chế tạo: cần cẩu điện, chuông điện, bếp điện, máy sấy tóc, điện thoại, bóng đèn sợi đốt (dây tóc) đúc tượng đồng, mạ kim loại, máy châm cứu, máy mát xa bằng điện, tinh luyện kim loại, bóng đèn cao áp đường phố…người ta đã ứng dụng tác dụng nào của dòng điện?
Tính hợp lý: 85:(-5)-7.(15-20)-(-9).(-2
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