How many middle school math questions to ask Middle school math questions?

Solution: f= a

Proof: Because EB and ED are both the radius of the circle E.

So EB=ED

b=∠edb

Because ab=ac

So b= acb

So edb= acb

So ed ac

Because ef=ab=ac

So the quadrilateral ACFE is a parallelogram.

So f= a

1) Proof: Because abc is an equilateral triangle.

So ac=bc, acb=b

And because cd=bf

So the triangle adc congruent triangle cfb

1. He got it right (19 questions).

The number of correct answers is x, and the number of incorrect questions is y. Column equation: x y 25, 4x y 70, x 19, y 6

2. The larger angle is (63)°

Let the two corners be x and y. Column equation: x y = 90, (180 x) (180 y) = 36, x 27, y 63

3. At this time, the direction in which he is going is (northeast or southwest).

The southeast direction is -45°, -45°, 90° 45°, -135°, that is, the northeast direction, the southwest direction.

4、|a+c|+|a+b+c|-|a-b|+|b+c|=（-3a-b-3c）

From the known conditions, a+c is negative, a+b+c is negative, a-b is positive, b+c is negative, then |a+c|＝-a-c，|a+b+c|＝-a-b-c，|a-b|＝a-b，|b+c|-b-c, so |a+c|+|a+b+c|-|a-b|+|b+c|＝（a-c）+（a-b-c）-（a-b）+（b-c）＝-3a-b-3c

1.Suppose the number of correct answers is x and the number of wrong questions is y, then x+y=25 4x-y=70 gives x=19 y=6

3.Northeast or Southwest.

4.-3a-2c-b

It's pretty similar, I didn't copy you.

1.True 19 False 6

3.Northeast or Southwest.

4. -3a-b-3c

Students do their own homework and strive to do it on their own. b

MonomialCoefficient: The numerical factor in the single remaining squirting term. For example:

The coefficient of 2xy is 2; The coefficient of -5zy is -5. The coefficient of 2 ab is 2.

So the coefficient of the first null: monomial "3 x y 4" is "3 4".

Number of monomials: The sum of the exponents of all variables in a monomial is called the number of times of the monomial. For example:

So the second null: the magnitude of the mononomial "3 x y 4" is 3.

Polynomials, each monomial is called an term of a polynomial; The highest number of times each term is called the number of times of the polynomial. A polynomial is a few terms, which is called a few terms.

So 2x -x y -3xy + x-1 is a 4th time 5nomial.

Because my son is in junior high school, he is really bad at math, and chain segmentation is a problem. As a parent, I must go to a math teacher to make up this math problem for my son, because he is in junior high school, after all, he has to go to college, and he must make up for this math.

The coefficient of the monomial is the number before the letter, the coefficient of this question is three-quarters of the faction, the attention faction is also the coefficient, and the degree is the sum of all the letter exponents, which is four.

Solution: 1, from the meaning of the topic, it is easy to know that if there is a minimum value, then k is greater than 0.

And the question can be converted to kx

(k-1)x+k-1=0 has only one root, and we get δ=(k-1) -4k(k-1)=0, and k is greater than 0

So k = 12, let xh after the two ships are separated by s, then s = root number [(15x) +125-20x) ] ] = root number [625x -5000x+125 ].

So when x=4, the closest distance between the two ships is 75km

3. Let the length of the line segment as one side of the square be xcm, and the length of the line segment as the hypotenuse of an isosceles right triangle is (10-x) cm

The sum of the areas of the two is s=x +(10-x) 4=5 4x -5x+25, where x is in the interval (0,10).

So when x=2, s has a minimum value of 20cm

Solution 1: Prove that the parallel lines of F as AB cross ac at h

Because f is the midpoint of de.

So fh=(1 2)ad, ah=he

And because ae=ec

So hc = (3 4)ac

So hf = (3 4)ag

ag=(4/3)hf

dg=ad-ag=2fh-(4/3)fh=(2/3)fhag：gd=2

Solution 2: The parallel lines of E as AB intersect CG at M

em=dgem=1/2ag

ag：gd=2

Solution 3: Connect af, then af is a midline of ade, so s adf s aef, because de is the median line of abc, so de bc 1 2, so df bc 1 4, and because de bc, gd gb df bc 1 4, so dg db 1 3, db ad, so dg ad 1 3

So dg ag 1 2, i.e.: ag:gd=2:1

1, the second way to draw is to take d, d1 midpoint e1, connect ae1 and e1c1, ae1c1 is the second shortest route.

The principle is very simple, that is, between two points, the line segment is the shortest.

You can see it by spreading out the three-dimensional box on a flat surface.

2.Let the length of c1g be x

cm.Then the length of GC is .

30-x)cm.

To make the time the shortest, f is the midpoint of BC, so af=fg = root (225 + (30-x) squared).

af+fg)/

You can find the value of x.

It's too much trouble. That's what I'm talking about.

The latter ones are counted by themselves.

How do you hit the root number?

From similar triangles, the corresponding sides are proportional and the corresponding angles are equal, and then the corresponding sides are proportional and the corresponding angles are equal, and the two triangles are similar.

First, the properties of similar triangles are used, and then the determination of similar triangles is used.