9. 计算:$(-1)^2 + (\frac{1}{3})^0 =$
2
.答案
9.2
10. 如果关于x的多项式$9x^2 - (m - 1)x + 4$是完全平 方式,那么m的值为
13或-11
。答案
10.13或-11
11. 新视角 新定义题 设 $a,b$ 是实数,定义关于“*”的一种运算如下:$a*b=(a+b)^2-(a-b)^2$,则下列结论:①$a*b=0$,则$a=0$或$b=0$;②不存在实数$a,b$,满足$a*b=a^2+4b^2$;③$a*(b+c)=a*b+a*c$;④$a*b=8$,则$(10ab^3)÷(5b^2)=4$。其中正确的是
①③④
(填序号)答案
11. ①③④ 【点拨】①$\because a * b = 0,\therefore (a + b)^2 - (a - b)^2 = 0.\therefore a^2 + 2ab + b^2 - (a^2 - 2ab + b^2) = 0.\therefore 4ab = 0.\therefore a = 0$或$b=0$.故①正确;②$\because a * b = (a + b)^2 - (a - b)^2 = 4ab$,$a * b = a^2 + 4b^2 ,\therefore a^2 + 4b^2 = 4ab.\therefore a^2 - 4ab + 4b^2 = (a - 2b)^2 = 0.\therefore a = 2b.\therefore$存在实数 $ a,b,$ 满足 $ a * b = a^2 + 4b^2 .$ 故②错误;③$\because a * (b + c) = (a + b + c)^2 - (a - b - c)^2 = 4ab + 4ac ,a * b + a * c = 4ab + 4ac ,\therefore a * (b + c) = a * b + a * c .$ 故③正确;④$\because a * b = 8,\therefore 4ab = 8.\therefore ab = 2.\therefore (10ab^3) ÷ (5b^2) = 2ab = 4.$ 故④正确.
12.若$(x-3)(x^2+ax+b)$的结果中不含$x$的二次项和一次项,则$a+b$的值为
12
答案
12. 12 【点拨】原式$= x^3 + ax^2 + bx - 3x^2 - 3ax - 3b = x^3 + (a - 3)x^2 + (b - 3a)x - 3b ,$由结果中不含 $ x $ 的二次项和一次项,得 $ a - 3 = 0 ,b - 3a = 0 ,$解得 $ a = 3 ,b = 9 ,$则$a + b = 3 + 9 = 12.$
13. $3(2^2 + 1)(2^4 + 1)(2^8 + 1)\dots(2^{32} + 1) + 1$ 计算结果的个位数字是
6
.答案
13.6
三、解答题(共48分)
14.(8分)计算:
(1)$2a^2 · a^4 + (-2a^2)^3 - a^8 ÷ a^2$;
(2)$2x(x - 3y) + (5xy^2 - 2x^2y) ÷ y$。
14.(8分)计算:
(1)$2a^2 · a^4 + (-2a^2)^3 - a^8 ÷ a^2$;
(2)$2x(x - 3y) + (5xy^2 - 2x^2y) ÷ y$。
答案
14. 【解】(1)$2 a^2 · a^4 + (-2 a^2)^3 - a^8 ÷ a^2 = 2 a^6 - 8a^6 - a^6 = -7 a^6$ .
(2)$2x(x - 3y) + (5xy^2 - 2x^2 y) ÷ y = 2x^2 - 6xy + 5xy - 2x^2 = -xy.$
(2)$2x(x - 3y) + (5xy^2 - 2x^2 y) ÷ y = 2x^2 - 6xy + 5xy - 2x^2 = -xy.$
15.(8分)计算:
(1) $99\frac{5}{7} × (-100\frac{2}{7})$;
(2) $1234^2 - 1234 × 268 + 134^2$。
(1) $99\frac{5}{7} × (-100\frac{2}{7})$;
(2) $1234^2 - 1234 × 268 + 134^2$。
答案
15. 【解】(1) $99 \frac{5}{7} × (-100 \frac{2}{7}) = - (100 - \frac{2}{7}) × (100 + \frac{2}{7}) = -[100^2 - (\frac{2}{7})^2] = -(10\ 000 - \frac{4}{49}) = -9\ 999\ \frac{45}{49}.$
(2)$1\ 234^2 - 1\ 234 × 268 + 134^2 = 1\ 234^2 - 2 × 1\ 234 × 134 + 134^2 = (1\ 234 - 134)^2 = 1\ 100^2 = 1\ 210\ 000.$
(2)$1\ 234^2 - 1\ 234 × 268 + 134^2 = 1\ 234^2 - 2 × 1\ 234 × 134 + 134^2 = (1\ 234 - 134)^2 = 1\ 100^2 = 1\ 210\ 000.$
16.(10分)母题 教材 P117习题 T4 先化简,再求值:
$[(2x - y)^2 - (3x + y)(3x - y) + 5x^2] ÷ (-2y)$,其中$x = -\frac{1}{2}$,$y = 1$。
$[(2x - y)^2 - (3x + y)(3x - y) + 5x^2] ÷ (-2y)$,其中$x = -\frac{1}{2}$,$y = 1$。
答案
16. 【解】原式$= (4x^2 - 4xy + y^2 - 9x^2 + y^2 + 5x^2) ÷ (-2y) = (2y^2 - 4xy) ÷ (-2y) = -y + 2x.$
当$x = -\frac{1}{2},y = 1$时,原式$= -1 + 2 × (-\frac{1}{2}) = -1 - 1 = -2.$
当$x = -\frac{1}{2},y = 1$时,原式$= -1 + 2 × (-\frac{1}{2}) = -1 - 1 = -2.$
17. (10分) 已知关于$ x $的多项式$ A $满足$ A - (x - 1)(x + 1) = (x + 1)^2 $。
(1) 求整式$ A $;
(2) 若$ B = 3x^2 + 4x + 2 $,当$ x = -\frac{1}{2} $时,求$ B - A $的值。
(1) 求整式$ A $;
(2) 若$ B = 3x^2 + 4x + 2 $,当$ x = -\frac{1}{2} $时,求$ B - A $的值。
答案
17. 【解】(1)$\because A - (x - 1)(x + 1) = (x + 1)^2 ,\therefore A = (x + 1)^2 + (x + 1)(x - 1) = x^2 + 2x + 1 + x^2 - 1 = 2x^2 + 2x.$
(2)$\because B = 3x^2 + 4x + 2 ,A = 2x^2 + 2x ,\therefore B - A = 3x^2 + 4x + 2 - (2x^2 + 2x) = 3x^2 + 4x + 2 - 2x^2 - 2x = x^2 + 2x + 2.$
当$x = -\frac{1}{2}$时, $B - A = (-\frac{1}{2})^2 + 2 × (-\frac{1}{2}) + 2 = \frac{5}{4}.$
(2)$\because B = 3x^2 + 4x + 2 ,A = 2x^2 + 2x ,\therefore B - A = 3x^2 + 4x + 2 - (2x^2 + 2x) = 3x^2 + 4x + 2 - 2x^2 - 2x = x^2 + 2x + 2.$
当$x = -\frac{1}{2}$时, $B - A = (-\frac{1}{2})^2 + 2 × (-\frac{1}{2}) + 2 = \frac{5}{4}.$
18.(12分)用图①中三种不同大小的正方形与长方形,拼成了一个如图②所示的正方形.
(1)根据图②中各部分的面积关系,直接写出代数式$(a+b)^2,a^2+b^2,2ab$之间的数量关系:
(2)根据完全平方公式的变形,解决下列问题.
①已知$m+n=5,mn=4$,求$m^2+n^2$和$(m-n)^2$的值;
②已知$(x-98)^2+(100-x)^2=34$,求$(98-x)(100-x)$的值.

(1)根据图②中各部分的面积关系,直接写出代数式$(a+b)^2,a^2+b^2,2ab$之间的数量关系:
$a^2 + b^2 = (a + b)^2 - 2ab$
;(2)根据完全平方公式的变形,解决下列问题.
①已知$m+n=5,mn=4$,求$m^2+n^2$和$(m-n)^2$的值;
②已知$(x-98)^2+(100-x)^2=34$,求$(98-x)(100-x)$的值.
答案
18. 【解】(1)$a^2 + b^2 = (a + b)^2 - 2ab$
(2)①$\because m + n = 5 ,mn = 4 ,$
$\therefore m^2 + n^2 = (m + n)^2 - 2mn = 25 - 2 × 4 = 17.$
$\therefore (m - n)^2 = m^2 + n^2 - 2mn = 17 - 2 × 4 = 9.$
②$\because 98 - x - (100 - x) = -2 ,$
$(98 - x)^2 + (100 - x)^2 = (x - 98)^2 + (100 - x)^2 = 34 ,$
$\therefore [(98 - x) - (100 - x)]^2 = 34 - 2(98 - x)(100 - x) ,$
即$4 = 34 - 2(98 - x)(100 - x). \therefore (98 - x)(100 - x) = 15.$
(2)①$\because m + n = 5 ,mn = 4 ,$
$\therefore m^2 + n^2 = (m + n)^2 - 2mn = 25 - 2 × 4 = 17.$
$\therefore (m - n)^2 = m^2 + n^2 - 2mn = 17 - 2 × 4 = 9.$
②$\because 98 - x - (100 - x) = -2 ,$
$(98 - x)^2 + (100 - x)^2 = (x - 98)^2 + (100 - x)^2 = 34 ,$
$\therefore [(98 - x) - (100 - x)]^2 = 34 - 2(98 - x)(100 - x) ,$
即$4 = 34 - 2(98 - x)(100 - x). \therefore (98 - x)(100 - x) = 15.$
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