Ask for two junior high school math fractional questions, and two junior high two math fractional mu

1) Solve the equation: 1 (x-7)+1 (x-4)=1 (x-6)+1 (x-5).

1/(x-7)+1/(x-4)=1/(x-6)+1/(x-5)

Scores. 2x-11)/(x-7)(x-4)=(2x-11)/(x-6)(x-5)

2x-11)[1/(x^2-11x+28)-1/(x^2-11x+30)]=0

Because x 2-11x+28 is not equal to x 2-11x+30

So 1 (x 2-11x+28)-1 (x 2-11x+30) is not equal to 0

So so 2x-11=0

x=11/2

Fractional equations to be tested.

After testing, x=11 2 is the solution of the equation.

2) Knowing (2x+3) x(x-1)(x+2)=a x+b (x-1)+c (x+2) (a,b,c is constant), find the value of a,b,c.

2x+3)/[x(x-1)(x+2)]=a/x+b/(x-1)+c/(x+2)

a(x^2+x-2)+b(x^2+2x)+c(x^2-x)]/[x(x-1)(x+2)]

a+b+c)x^2+(a+2b-c)x-2a]/[x(x-1)(x+2)]

It can be obtained: a+b+c=0

a+2b-c=2

2a=3a=-3/2

b=5/3c=-1/6

There is no solution to the first question. The second problem is divided into a(x-1)(x+2)+bx(x+2)+cx(x-1)=2x+3, and the coefficients of the unknowns on both sides of the equation are a+b+c=0, a+2b-c=2, -2a=3, a=-3 2, b=5 3, c=-1 6

Answer: 1) From the known, there are: m=1, n=2xy (x 2+y 2) from the basic inequality: x 2+y 2>=2xy, so: n<=1

To sum up, there is: n<=m, choose a

2) Multiply both ends of the equation by x(x+1)(x-1) at the same time, and get: 7(x-1)+(x+1)=6x, i.e.: 2x=6

Solution: x=3

So: choose B

m-n=x²+y²/x²+y²-(2xy/x²+y²)(x²+y²-2xy)/(x²+y²)

x-y) x +y ) 0m n choose a

7 x +x +1 x -x=6 x -1 is obtained by removing the denominator. 7（x-1)+x+1=6x

7x-7+x+1=6x

2x=6x=3

It is verified that x=3 is the root of the original equation. Pick B

The equation should be 3, I don't know if the x2+x is the denominator part, it's okay with the band, it's very easy.

According to: 1) Yield per unit area = total output area, 2) Compare the size of the difference method, if a-b 0then a b

Solution: 1) Area yield of a rice experimental field: 500 (A -1) B area yield of a rice experimental field:

500 (a -1) Because (a 1)-(a-1) = a -1-(a -2a+1)=a -1-a +2a-1=2a-2=2(a-1) 0, so (a 1) (a-1).

Therefore, 500 (a -1) and 500 (a -1) i.e. the area yield of the B rice experimental plot is high.

2)【500/(a -1)²】500/(a² -1)】=(a² -1)/(a -1)²=(a+1)/(a-1)

Multiply xy on both sides to get y-x=2xy, x-y=-2xy into the original formula, and get -xy -4xy=1 4

Divide x by both sides to get x+3+1 x=0, then we get x+1 x=3 And because x +1 x =(x+1 x) -2, bring x+1 x=3 into the original formula, and we get x +1 x =9-2=7

4.(1) Simplification yields -1 (x -11x+30) = -1 (x -17x+72), then x -11x+30=x -17x+72, x=7

2) Make the product of each denominator 2 (2x-2) (3x-3), you can get 10x -16x+6=6x -12x+6, simplify, get 4x =4x, x=1

1、a＝2,b＝2；b²+a²＝8；

The following can't be seen clearly, the third question is not understandable at all, the second question is not clear, please write the question clearly, like the first question should be written as 4x (x -4) = a (x + 2) + b (x-2), if your question is okay, I will not do it.

From the meaning of the title, the distance between the two places is 14 (4+10) kilometers, and if the walking speed is x, the speed of cycling is x+8, and the speed of taking a car is x+24, and the round-trip time is equal to the equation:

4/x+10/(x+24)=14/(x+8)

Solve the equation to get x=6km h.

If the speed of walking is x km/h, the speed of cycling is x+8 and the speed of riding a car is x+24

The equation is obtained according to the round-trip time equal.

4/x+10/(x+24)=14/(x+8)x=8/3

So the person walks at a speed of 8-3 km/h.

There's something wrong with your question! It should be 1 a-1 b=3! If this is known to be the case, then the result is 5 3. First divide the known generals, then sort out a-b=-3ab, and then replace a-b with -3ab in the verification!

You want to express: 1 a-1 b = 3, find (2a+3ab-2b) (a-2ab-b) instead of"a/1"(1/a)? As I understand it, the answer is as follows:

1 a-1 b=3, then (b-a) ab=3, i.e., b-a=3ab, a-b=-3ab

2a+3ab-2b)/(a-2ab-b)=[2(a-b)+3ab]/[(a-b)-2ab]=(-3ab)/(-5ab)=3/5

1/A - 1/1 b = 3 ??

It should be 1 a-1 b=3 The title is written confusingly.

Because 1 a-1 b=3, b-a=3ab(a-2ab-b) (2a+3ab-2b)=(-5ab) (-3ab)=5 3

1) The simplest common denominator of x 2y and 2 3xy squares: 6xy

2) 2 9 3a +a 1 a square 9=-2 3a-9 +a 1 a square 9 the simplest common denominator 3 (a-3) (a+3).

Solution: The simplest common denominator of x 2y and 2 3xy is 6xy; 2 (9-3a), and the common denominator of (a-1) (a -9) is -3(3-a)(3+a).

When two places meet S kilometers, the speed of the ship in still water is a kilometer, and the speed of the current is B kilometers, then the time required for the ship to make a round trip.

s/(a+b)+s/(a-b)