Ask your math teacher to solve a junior high school algebra problem

The condition in the original question should be cd=6cm, right?

The book is titled, and I have done it.

Make op ab at p and symphony cd at point q

ab‖cdoq⊥cd

According to the perpendicular diameter theorem, it can be obtained: ap=bp=4, cq=dq=5oa=oc=5

According to the Pythagorean theorem, it can be obtained: op = 3 cm, oq = 4 cm when ab, cd is on the same side of the center of the circle, pq=4-3 = 1cm when ab, cd is on the opposite side of the center of the circle, pq=4+3=7cm, that is: ab, the distance between cd is 1cm or 7cm

Let cd=2x(0 distance is 3+5-x 2 under the root number

Just draw a picture.

Connect ob od over o do om perpendicular ab on m on perpendicular cd on n distance is the sum of the two right-angled sides of the two triangles.

Even AO, AB, do OQ perpendicular to AB, OP perpendicular to CD because diameter = 10cm

So ao=ab=5cm

Because ab=8cm

So AQ = 4cm

Pythagorean theorem, so oq = 3cm

In the same way, op=3 2 roots number 11cm

So pq = 3cm + -3 2 root number 11cm

Then the distance between the chord AB and CD is (1 cm or 7 cm) solution: ab = 8 cm, cd = 6 cm, ab and cd are on the same side of diameter.

then d = 4-3 = 1cm

AB and CD are on opposite sides of diameter.

then d = 4 + 3 = 7 cm

Not good! Schoolmate! cd=cm？I guess it's cd=6cm! The answer should be 1cm or 7cm!

No, it seems that there is a condition missing, how to do it? You'd better send the picture in.

There are two scenarios.

1.(ab cd on the ipsilateral side) connects the center of the circle and a, and connects o and c. Passing point O to do AB vertical OE, crossing point O to do CD vertical of.

Let oe be x of y x=3 y=4 so the distance is 1cd on the opposite side) to connect the center of the circle and a, and connect o and c. Passing point O to do AB vertical OE, crossing point O to do CD vertical of.

Let oe be x of y 5 2=x 2+4 2 x=35 2=y 2+3 2 y=4 so the distance is 7

cd=cm is missing a value. Who did it.

It seems to be less conditional. Preferably on the map.

x:2y=3:4

This means that x 2y=3 4, multiply diagonally.

4x=6y

17(a+

17 (a + a = let the water use be x, the maximum cost y (x table qing oak y function) the maximum cost of water use = 184

According to the conditions, the rent is poor and filial piety x>25

3x x≤17

y=17*3+(x-17)*5=5x-34 1730x=30

1、t/x-ab+88

Because t, x, a, and b are letters, they conform to the concept of algebraic formulas; 88 is a number, which conforms to the concept of algebraic; , is an operation symbol, in line with the concept of algebra. That is, every part of the equation conforms to the concept of algebraic formulas.

So,"t/x-ab+88"is algebraic.

x+33=188

Because x is a letter, it conforms to the algebraic concept It is a number, which conforms to the algebraic concept; , is an operation notation, in line with the concept of algebra. However, "= is not an operation symbol, it is a relational symbol, which does not conform to the algebraic concept. In other words, there is a part of this equation that does not conform to the concept of algebraic formulas.

So,"7/x+33=188 "Not algebraic.

3. A b because a and b are letters, in line with the concept of algebraic formula; However, "Pei Lao is not an arithmetic symbol, it is a relational symbol, which does not conform to the algebraic concept. In other words, there is a part of this equation that does not conform to the concept of algebraic formulas.

So,"a≥b"Not algebraic.

4、a:b:c

Because a, b, and c are letters, they conform to the concept of algebraic formulas; ": is an operation notation that conforms to the concept of algebraic formulas. That is, every part of the equation conforms to the concept of algebraic formulas.

So,"a:b:c"is algebraic.

Because it is a number, it conforms to the concept of algebraic; However, "= is not an operation symbol, it is a relational symbol, which does not conform to the algebraic concept. In other words, there is a part of this equation that does not conform to the concept of algebraic formulas.

So,"3+8=11"Not algebraic.

Because it is a number, it conforms to the concept of algebraic; ": is an operation notation that conforms to the concept of algebraic formulas. That is, every part of the equation conforms to the concept of algebraic formulas.

So,"√16+4"is algebraic.

Because it is a number, it conforms to the concept of algebraic; The power and "-" are operational symbols, which conform to algebraic concepts. That is, every part of the equation conforms to the concept of algebraic formulas.

So,"8-6"is algebraic.

8、a≈168

Because 168 is a number, it fits the algebraic concept; However, "= is not an operation symbol, it is a relational symbol, which does not conform to the algebraic concept. In other words, there is a part of this equation that does not conform to the concept of algebraic formulas.

So,"a≈168"It is not a pure algebraic formula in a modulo.

Find out xy, bring it in and you can calculate it.

Whether it is y=kx+k-1 and y=(k+1)x+k, first express the intersection point of the two straight lines c(-1,-1), and the intersection point with the x-axis is a( 1-k k,0), b(-k k+1,0), the length of the bottom edge ab ab=(1-k k)-(k k+1)=1 k(1+k), the height is the absolute value of the ordinate of the c point 1, and the area of the triangle enclosed by the x-axis is sk=1 2*1 k(1+k),s1+s2+.s2006=1/2x(1/1x2+1/2x3+1/3x4...1/2006x2007)=1/2x(1-1/2+1/2-1/3+1/3-1/4+..

1/2006-1/2007)=1/2x(1-1/2007)=1/2x2006/2007=1003/2007

Draw a virtual force diagram, when k=1, draw the plot, calculate the area = 1 2[k (k+1)];

Then substitute the calculation.

Find the law The intersection points of the two line segments on the y-axis are 1, and the intersection points on the x-axis are -k (k+1), -k-1) k, and the subtraction of the two is the length of the other right-angled side of the triangle The two want to multiply and multiply by half is the area sk=1 2[k*(k+1)];

This question is a bit difficult, and it is generally not taken in the high school entrance examination.

1) I didn't use the iterative method for this question.

a+1 b=1, and the score is ab+1=b, ab=b-1......b+1 c=1, and the general score is obtained as bc+1=c, bc=c-1......AB c=(b-1)(c-1)ab c=bc-b-c+1

ab²c=(c-1)-b-(c-1)

ab²c=-b

b≠0abc=-1……③

Substituting , AB=B+ABC

Because b≠0

a=ac+1

a≠0 is divided by a

This gives c+(1 a)=1

2）x²-y²-z²=0

y²=x²-z²，z²=x²-y²

x³-y³-z³

x³-y³)-z(x²-y²)

x-y)(x²+xy+y²)-z(x+y)(x-y)=(x-y)(x²+xy+y²-zx-zy)=(x-y)[x²+xy+(x²-z²)-zx-zy]=(x-y)[(x²-xz)+(x+z)(x-z)+(xy-zy)]=(x-y)[x(x-z)+(x+z)(x-z)+y(x-z)]=(x-y)(x-z)[x+x+z+y]

x-y)(x-z)(2x+y+z)

So a=2x+y+z

Hope it helps].

The first problem cannot be a definite number, but any real number with a range other than 1.

The first answer is equal to one, and it is okay to use the iterative method.

I'll do the first question.

You can do it with a general score, and I'll demonstrate it first:

a+1 b=1 pass: (ab+1) b=1 multiply b at both ends of the equation at the same time, and simplify it to obtain:

b=1/(1-a)(1)

The same goes for it: c = 1 (1-b) (2).

In the same way, c+1 a=(ac+1) a substituting (1) and (2) that is, replacing the letters b and c with the letters a, and the final result a a=1

It's not complicated! Typing is time-consuming.

A can't be a one-time polynomial!

Answer: Let the largest three-digit number be 100a+10b+c, then the smallest three-digit number is 100c+10b+a, the two numbers are subtracted = 99 (a--c), by 1 c 7, 3 a 9, so a--c, then 99 (a--c, these 7 results, so a, b, c must have the number 9, the sum of the other two numbers = 9, so a, b, c three numbers can only be the above 7 cases, discuss and judge separately to obtain the result

In fact, this kind of question can only have a sense of accomplishment when you think of it yourself, this cannot be homework, it is homework and the last big question, and it is not a must.

To give you a beginning: three minus three equals three, the hundred must be the largest number minus the smallest number, and the largest number is also in the number, the largest number plus one number is actually equal to the smaller number than the largest, so it is certain that the largest number plus any one of the remaining two must be greater than ten, and then you think again... Anyway, there is an answer, hehe.

If none of the three numbers is zero, then they must subtract to get a zero, so one of them must be zero.

Because if there is no zero, the maximum and minimum are subtracted, and the resulting quotient must be zero in the middle, so none of the three numbers is zero. Let's move on**.

When y1=y2+5, x+3=2-x+5, the shift is combined with similar terms to get 2x=4, so x=2