7th Grade Mathematics, 1st Question, 7th Grade Mathematics 1 Question

Because ac=ab, acb=90, so b=45, so be=de, the triangle acd is all equal to the triangle aed(aas), so cd=de=eb, let eb be x, db=root2 x, ab=10, cb=5, root2, x+root2 x=5, root2, x=...Let's figure it out for myself later.

First of all: how to get x 8 and x 4

x 4 can be obtained from x*x 3.

It can also be obtained from x 2 x x 2.

It can also be obtained from 1*x4.

In the same way, the coefficient of x 8 is 2*2+3-3*7=-14x4, and the coefficient of 4 is -5*4-2*1=-22

（2x^6-3x^5+4x^4-7x^3+2x-5)(3x^5-x^3+2x^2-5)

6x^11-9x^10+10x^9-14x^8-10x^7+4x^6-14x^5-22x^4+44x^3-10x^2-10x+25

So the coefficients of x 8 and x 4 are -14 and 22, respectively

The seventh grade is the first year of junior high school, so I still think about Li Tian. The process is as follows:

2a-7b)x+（3a-8b）=8x+102a-7b-8)x=10-3a+8b

Because the solution of x is a real number.

So there are 2a-7b-8=0 and 10-3a+8b=02a-7b-8=0(1).

10-3a+8b=0（2）

Obtained from (2).

3a-8b-10=0 （3）

3)—(1), get: sleepy training.

a-b-2=0

a=b+2 (4)

Substitute (4) into (1) to get.

b = -(4 5) substituting (4), get.

a=6/5

Because (2a-7b) x + (pin pure 3a-8b) swim tank = 8x + 10, so 2a-7b = 8

3a-8b=10

So a=6 5 b=-4 God Doutong 5

The equation is two noisy and coincidentally compared to Bi Bu Staring, getting.

2a-7b=8

3a-8b=10

The final hand and final solution get a= b=

x + 1/x = 4

x 2 + x 1/2 = 14

x-1/x = -2 3

Solution: From what is known: x1+x2=4, x1*x2=1, then x2=1 x1

Therefore: x1+1 x1=x1+x2=4

i.e. x+1 x=4;

(x+1 x) 2=x 2+2+1 x 2=16, so x 2+1 x 2=16-2=14;

Because (x-1 x) 2=x 2-2+1 x 2=14-2=12, x-1 x=2 3 or -2 3

Because 01 is x<1 x

x-1 x<0

Therefore x-1 x=-2 3

If there are x people participating in the English competition, then the number of people participating in the mathematics competition (x+5) will be x+(x+5)-20=45 according to the title

Solve x = 30 30 + 5 = 35 people.

That is, 30 people participated in the English competition and 35 people participated in the mathematics competition.

There are x people who participate in the English competition and y people who participate in the mathematics competition, and there are y-x=5 according to the title

x+y-45=20

The solution is x=30 y=35

That is, 30 people participated in the English competition and 35 people participated in the mathematics competition.

If there are x people in the English competition, then there will be (x+5) people in the math competition.

x+(x+5)-20=45

The solution yields x=30, x+5=35

Suppose that the number of participants in the English competition is x, and the number of participants in the mathematics competition is x+5

x+x+5-45=20

x=30 (person).

If there are x people participating in the English competition, then there are people participating in the mathematics competition (x+5), so x+(x+5)-20=45

So x=30

So 30 people participated in the English competition.

Answer. If there is y= then the knowledge pin (x-8) + 8-x) + 3 4 gives x-8 the great grandson swims in the fierce disturbance equal to 0

8-x is greater than or equal to 0

Hence x=8y=3 4

So 2x y=2*8*3 4=12