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電子課本網(wǎng) 第71頁(yè)

第71頁(yè)

信息發(fā)布者:
?$\frac 1{a}$?
?$a+b$?
?$\frac {2x}{x-3}$?
?$\frac 1{x-y}$?
B
A
解:原式?$=\frac {x-3+x+3}{(x-3)(x+3)}$?
?$ =\frac {2x}{x2-9}$?
解:原式?$=\frac {(a+b)c-(b+c)a}{abc}$?
?$ =\frac {b(c-a)}{abc}$?
?$ =\frac {c-a}{ac}$?
解:原式?$=\frac {3x-x-2}{x(x-1)}$?
?$ =\frac {2x-2}{x(x-1)}$?
?$ =\frac {2}{x}$?
解:原式?$=\frac {(y+2)(y-2)}{y-2}+\frac {4}{y-2}$?
?$ =\frac {y^2}{y-2} $?
解?$:\frac {100}{a}-\frac {100}{2a}=\frac {50}{a}($?臺(tái))
解:$(1)\frac {1}{x}+\frac {2}{3x}=\frac {5}{3x}(\mathrm {h})$
$(2)\frac {5}{3x}-\frac {3}{2x}=\frac {1}{6x}(\mathrm {h})$
∴走第一條路花費(fèi)時(shí)間少,少用$\frac {1}{6x}h$