10. 解方程:$\frac {2}{x+3}+\frac {3}{2}= \frac {7}{2x+6}$.
答案
x = -2
11. 响应“家电下乡”的惠农政策,某商场决定从厂家购进甲、乙、丙三种不同型号的电冰箱$80$台,其中甲种电冰箱的台数是乙种电冰箱台数的$2$倍,购买三种电冰箱的总金额不超过$132000$元.已知甲、乙、丙三种电冰箱的出厂价格分别为$1200$元/台、$1600$元/台、$2000$元/台.
(1)至少购进乙种电冰箱多少台?
(2)若要求甲种电冰箱的台数不超过丙种电冰箱的台数,则有哪些购买方案?
(1)至少购进乙种电冰箱多少台?
(2)若要求甲种电冰箱的台数不超过丙种电冰箱的台数,则有哪些购买方案?
答案
解:(1)设购买乙种冰箱x台,则购买甲种冰箱2x台,丙种冰箱(80 - 3x)台.依题意有:1200×2x + 1600x + (80 - 3x)×2000 ≤ 132000,解得x ≥ 14,∴至少购进乙种冰箱14台.(2)依题意,得2x ≤ 80 - 3x,解得x ≤ 16.由(1)知x ≥ 14,∴14 ≤ x ≤ 16,又x为整数,∴x = 14,15,16.∴有三种方案:方案1:甲28台,乙为14台,丙38台;方案2:甲30台,乙15台,丙35台;方案3:甲32台,乙16台,丙32台.
12. 在平面直角坐标系中,四边形ABCD的位置如图所示,解答下列问题:
(1)将四边形ABCD先向左平移4个单位长度,再向下平移6个单位长度,得到四边形A_{1}B_{1}C_{1}D_{1},画出平移后的四边形A_{1}B_{1}C_{1}D_{1};
(2)将四边形A_{1}B_{1}C_{1}D_{1}绕点A_{1}逆时针旋转$90^{\circ }$得到四边形A_{1}B_{2}C_{2}D_{2},画出旋转后的四边形A_{1}B_{2}C_{2}D_{2}.并写出点C_{2}的坐标.
(1)四边形A_{1}B_{1}C_{1}D_{1}如图所示;(2)四边形A_{1}B_{2}C_{2}D_{2}如图所示,C_{2}(
(1)将四边形ABCD先向左平移4个单位长度,再向下平移6个单位长度,得到四边形A_{1}B_{1}C_{1}D_{1},画出平移后的四边形A_{1}B_{1}C_{1}D_{1};
(2)将四边形A_{1}B_{1}C_{1}D_{1}绕点A_{1}逆时针旋转$90^{\circ }$得到四边形A_{1}B_{2}C_{2}D_{2},画出旋转后的四边形A_{1}B_{2}C_{2}D_{2}.并写出点C_{2}的坐标.
1,-2
).答案
解:(1)四边形$A_{1}B_{1}C_{1}D_{1}$如图所示;(2)四边形$A_{1}B_{2}C_{2}D_{2}$如图所示,$C_{2}(1,-2)$.
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