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1. 若一个数的倒数是$-3\dfrac{1}{4}$，则这个数是（
A.$\dfrac{4}{13}$
B.$-\dfrac{4}{13}$
C.$\dfrac{13}{4}$
D.$-\dfrac{13}{4}$
B
）A.$\dfrac{4}{13}$
B.$-\dfrac{4}{13}$
C.$\dfrac{13}{4}$
D.$-\dfrac{13}{4}$
答案
1.B
2. 下列计算中正确的是（
A.$(-100)+23=-123$
B.$0 - (-\dfrac{1}{3})=\dfrac{1}{3}$
C.$\dfrac{3}{4} - \dfrac{3}{4} × 8=0$
D.$(-5) ÷ (-\dfrac{1}{5})=1$
B
）A.$(-100)+23=-123$
B.$0 - (-\dfrac{1}{3})=\dfrac{1}{3}$
C.$\dfrac{3}{4} - \dfrac{3}{4} × 8=0$
D.$(-5) ÷ (-\dfrac{1}{5})=1$
答案
2.B
3. 与下面科学计算器的按键顺序对应的计算任务是（
( (-) 1 5
$y^x$ 4 ÷ 5 $x^2$
A.$-15^4 ÷ 5 × 2$
B.$-15^4 ÷ 5^2$
C.$(-15)^4 ÷ 5 × 2$
D.$(-15)^4 ÷ 5^2$
D
）( (-) 1 5
$y^x$ 4 ÷ 5 $x^2$A.$-15^4 ÷ 5 × 2$
B.$-15^4 ÷ 5^2$
C.$(-15)^4 ÷ 5 × 2$
D.$(-15)^4 ÷ 5^2$
答案
3.D
4. 根据流程图中的程序,若输入x的值为-1,则输出y的值为 (
A.-2
B.5
C.7
D.142
C
)A.-2
B.5
C.7
D.142
答案
4.C
5. 使式子:$1□(\frac{1}{3}+\frac{1}{4})×(-12)$的运算结果为正整数，“$□$”中的运算符号为（
A.+
B.-
C.×
D.÷
B
）A.+
B.-
C.×
D.÷
答案
5.B
6. 计算:
(1) $(-\dfrac{12}{5})-[7 - (-3.2) + (-1)];$
(2) $-36 ÷ \dfrac{6}{5} × \dfrac{5}{6} × (-\dfrac{2}{5});$
(3) $-6^2 × (\dfrac{3}{4} - \dfrac{1}{2} - \dfrac{5}{9}) - 36\dfrac{4}{9} ÷ 2^2 - (-1)^3;$
(4) $-1^2 + (3 - 5)^2 - \left| -\dfrac{1}{4} \right| ÷ (\dfrac{1}{2})^3.$
(1) $(-\dfrac{12}{5})-[7 - (-3.2) + (-1)];$
(2) $-36 ÷ \dfrac{6}{5} × \dfrac{5}{6} × (-\dfrac{2}{5});$
(3) $-6^2 × (\dfrac{3}{4} - \dfrac{1}{2} - \dfrac{5}{9}) - 36\dfrac{4}{9} ÷ 2^2 - (-1)^3;$
(4) $-1^2 + (3 - 5)^2 - \left| -\dfrac{1}{4} \right| ÷ (\dfrac{1}{2})^3.$
答案
(1)解:原式 = -11.6.
(2)解:原式 = 10.
(3)解:原式 = $2\dfrac{8}{9}$.
(4)解:原式 = 1.
(2)解:原式 = 10.
(3)解:原式 = $2\dfrac{8}{9}$.
(4)解:原式 = 1.
7.【阅读理解】定义一种新运算:$a*b=a^2 - b + ab$.
例如:$1*2=1^2 -2 +1×2=1$.
(1)求$2*3$的值;
(2)求$(-2)*[2*(-3)]$的值.
例如:$1*2=1^2 -2 +1×2=1$.
(1)求$2*3$的值;
(2)求$(-2)*[2*(-3)]$的值.
答案
(1)原式 = 7.
(2)原式 = 1.
(2)原式 = 1.
