Class hour test 40 points seventh grade volume I math answers The integral (k2-9) X3 + (K-3) x2-k of X is known (1) If it is quadratic, find the value of K2 + 2K + 1 (2) If it's a binomial, find the value of K Note: except for the value of 2K + 1, the 2 decimal digits of 2K are all square decimal digits

(1) Because the integral in the question is quadratic, the coefficient K ^ 2-9 before x cube is 0, and the coefficient K-3 before x square is not equal to 0. At the same time, the K value satisfying these two conditions is k = - 3
(2) Because the integral in the question is binomial, then the trinomial given by the question should disappear one term. At this time, we have to discuss it in categories: when the constant term is to disappear, - k = 0, that is, k = 0
When the second term disappears, K-3 = 0, that is, k = 3. At this time, the first term disappears with it, which is against the theme
When the first term disappears and the second term does not disappear, then K ^ 2-9 = 0 and K-3 is not equal to 0
To sum up, when k = 0 or - 3, the integral is binomial

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Class hour test 40 points
Page 52 question 16: we know the equation 3x + 2A = x + 7 about X. when solving this equation, a student accidentally copied the plus 7 on the right side of the equation into minus 7, and the result of the solution is x = 2, so we can find the solution of the original equation
Page 54 question 13: there is a column of numbers, arranged into 1, - 4,16, - 64256,... According to certain rules, in which the sum of some three adjacent numbers is 3328, what are the three numbers?
Page 55 question 5: when a ship goes back and forth between ports a and B, it takes 3 hours to sail upstream and 3 hours to sail downstream. The water speed is 3 kilometers per hour. What is the speed of the ship in still water, km / h?
Page 56 question 13: given that the solution of equation 2 (kx-1) = (K + 2) x + 1 about X is a positive integer and K is an integer, find the solution of equation K (x-1) - 4 = (K + 1) (3x-4) about X

1. Calculate 2A first, and then substitute the value of 2A into 3x + 2A = a + 7
Substitute x = 2 into the equation
3X+2A=X-7
2*3+2a=2-7
6+2a=2-7
2a=2-7-6
2a=-11
A=-6.5
The value of a = 6.5 is substituted into the original formula
3X+2A=X-7
3X-11=X-7
3X-X=11-7
2X=4
X=2
2. Let the first number be x, the second number be - 4x, and the third number be 16x
x+(-4x)+16x=3328
(1-4+16)x=3328
13x=3328
x=256
-4X=-1024,16X=4096

As shown in the figure, in ladder ABCD, ad is parallel to BC, ad = AB = DC, ∠ BAC = 108 °, if BC = 10, Mn is the symmetry axis of ladder, P is a point on Mn, then PD + PC
The minimum value of is -- the picture can't be transferred,
I'll take the monthly exam tomorrow

Connect AC
Mn is the axis of symmetry,:. PD = PA,:. PD + PC = PA + PC
In PAC, when p, a and C are collinear, the sum of them is at least equal to AC

1、1995+1996+1997+1998+1999+2000 2、199999+19999+1999+199+19

1.
2000*5-1-2-3-4-5=10000-15=9985.
two
200000+20000+2000+200+20-5=222220-5=222215

Guess from the ancient poem
1、 Guess the name of the mountain
1. Only the sky is above, and there is no mountain
2、 Guess animals
1. A hundred songs and a thousand sounds move at will, the mountain flowers are red and the purple trees are high and low
2. When the hair color starts, it should be called
3、 Guessing place names
1. Surrounded by mountains, the country is surrounded by tides and empty cities
2. The river is full of rain, the river is full of grass, the Six Dynasties are like a dream, the birds are singing in the air
4、 Guess plants
1. A thousand whets and ten thousand blows, but still strong, let the East, West, North and south wind
5、 Guess the natural phenomenon
1. Thousands of things are still empty, reflecting water and Tibetan mountains
2. What's the matter with Fengnian
3. If you shed three autumn leaves, you can blossom in February
There is another way: guess animals: drink clear dew, flow out of Shutong

1、 Guess the name of the mountain
1. Only the sky is above, and there is no mountain and Qi. (Hua Shan)
2、 Guess animals
1. A hundred songs and a thousand sounds move at will. The mountain flowers are red and the purple trees are high and low. (thrush)
2. When the color of hair starts, it should be called by its own name. (duck)
3、 Guessing place names
1. Surrounded by mountains, the country is surrounded by tides, empty cities and lonely returns. (Nanjing)
2. The river is rainy, the river is full of grass, the Six Dynasties are like a dream, the birds are singing in the air. (Taicheng)
4、 Guess plants
1. A thousand whets and ten thousand blows, but still strong, let the East, West, north, south wind blow. (bamboo)
5、 Guess the natural phenomenon
1. Thousands of things are still empty, reflecting water and Tibetan mountains. (cloud)
2. What's the matter in a good year? (snow)
3. Leaves fall in three autumn and flowers bloom in February

As shown in the figure, the known point F is the midpoint of the side BC of the square ABCD, CG bisects ∠ DCE, GF ⊥ AF

It is proved that: take the midpoint m of AB, connect FM. ∵ point F is the midpoint of the side BC of the square ABCD, ∵ BF = BM, ∵ BMF = 45 °, ∵ AMF = 135 °. ∵ CG bisection ∵ DCE, ∵ GCE = 45 °, ∵ FCG = 135 °, ∵ AMF = ∵ FCG. ∵ B = 90 °, ∵ fam = 90 ° - ∵ AFB, ∵ GF ⊥ AF, ∵

Recursive equation calculation: 75 × 1 / 4 + 25 × 25%

Original formula = 75 × 25% + 25 × 25%
=（75+25）×0.25
=100×0.25
=25

Open quadratic radical 1 ~ 100

Root number 1 = 1 root number 4 = 2 root number 9 = 3 root number 16 = 4 root number 25 = 5 root number 36 = 6 root number 49 = 7 root number 64 = 8 root number 81 = 9 root number 100 = 10

If AB = 8, CD = 2, AE divides the trapezoid into △ Abe and quadrilateral adce, and their perimeter difference is 4, then the length of the trapezoid's waist ad is ()
A. 12b. 10C. 2 or 10d. 2 or 12

The perimeter of Abe is: ab + AE + be = 8 + AE + be; the perimeter of quadrilateral adce is: AD + CD + CE + AE = AD + 2 + AE + CE. According to the meaning of the question, we can get: (8 + AE + be) - (AD + 2 + AE + CE) = 4 or (AD + 2 + AE + CE) - (8 + AE + be) = 4; and ∵ be = CE, that is: ad = 4 or AD + 2-8 = 4, we can get ad = 2 or 10

If the result of the square of a polynomial is the square of 4A plus the square of 12ab plus the square of M, then M = what

12 divided by 2 = 6
6 divided by the root 4 = 3
So m = 3B
It's hard to answer. I hope you can adopt it

As shown in the figure, in ladder ABCD, ad is parallel to BC, ad = AB = DC, ∠ BAC = 108 °, if BC = 10, Mn is the symmetry axis of ladder, P is a point on Mn, then PD + PC The minimum value of is -- the picture can't be transferred, I'll take the monthly exam tomorrow