The calculation process of one variable linear equation 15x+11(25-x）=221

The calculation process of one variable linear equation 15x+11(25-x）=221

15x+11(25-x）=221
15x+275-11x=221
15x-11x=221-275
4x=-54
x=-13.5

Find 20 difficult one variable equation calculation problem, fast

Junior one mathematics, to detailed process, thank you, urgent (fractional multiplication and division)
1. Are the following calculations correct? If not, please correct
（1）1/a*a=1 （2）1/x-1/（x-1）=1
2. Calculation
(1) B / A & # 178; multiply a / b (2) AC & # 178 / 3B three times by 9b / A & # 178; C
(3) - 2b / 7xy & # 178; divided by 14ab / X & # 178; Y (4) 10MN divided by - 2n thrice / 5m
3. Calculation
(1) X & # 178; - Y & # 178 / XY times X / X-Y (2) a / A & # 178; + 6A + 9 divided by a & # 178 / A + 3

1. Is the following calculation correct? If not, please correct. (1) 1 / A * a = 1 -- correct. (2) 1 / X-1 / (x-1) = 1 -- wrong. 2. Calculate (1) B / A & # 178; multiply a / b = 1 / a (2) AC & # 178 / 3B three times by 9b / A & # 178; C = C / 3B ^ 2 (3) - 2b / 7xy & # 178; divide by 14ab / X & # 178; y = - 2b

It is known that the parabola y = x ^ 2 + BX + C has only one intersection point a with the axis
If the intersection of the parabola and the y-axis is B, the origin of the coordinate is O, and the triangle OAB is an isosceles triangle, find the analytical formula of the parabola and explain how it is translated from the parabola in (1)

Let x = 0, then y = C, so point B (0, c), because the parabola y = x ^ 2 + BX + C has only one intersection point a with the axis, so let y = 0
Discriminant = 0, so B ^ 2-4c = 0, and the root of equality is x = - B / 2, so a (- B / 2,0). Because the triangle OAB is isosceles triangle, we can know that OA = ob, so - B / 2 = C, from the above two conditions: C = 1 or C = 0 (rounding off), B = - 2
The analytic formula of parabola is y = x ^ 2-2x + 1
It can be reduced to: y = (x-1) ^ 2, which is obtained by translating y = x ^ 2 one unit to the right

It is known that the vertex of parabola C is at the origin of coordinate,
The focus is f (1,0), and the line L intersects the parabola at two points a and B. if the midpoint of AB is (2,2), then the linear equation L is
It is known that the vertex of the parabola C is at the origin of the coordinate, the focus is f (1,0), and the line L intersects the parabola at two points a and B. if the midpoint of AB is (2,2), then the linear equation L is

y=x

Complete steps of solving equations X / 4 + Y / 3 = 7,2 / 3x + 1 / 2Y = 14
Complete steps required

x/4+y/3=7 ①
2/3x+1/2y=14 ②
From (1) we get: 3x + 4Y = 84
From the result of 2, 4x + 3Y = 84
②-①：4x+3y-3x-4y=0
x=y

Given X / y = 3, find x · x + 2xy-3y · Y / X · x-xy + y · y
X · x, y · y is the square of X, which means the square of Y

x=3y
So xy = 3Y & sup2;
x²=9y²
So the original formula = (9y & sup2; + 6y & sup2; - Y & sup2;) / (9y & sup2; - 3Y & sup2; + Y & sup2;)
=14y²/7y²
=2

Application of quadratic equation of one variable
Company a and company B are going to rent the first floor of M Street shop separately. Company a's condition is: the annual rent is 290000 yuan; company B's condition is: the first year's rent is 200000 yuan, and then the annual rent is increased by the same percentage as that of the previous year, and the total rent of a company in three years is 2000 yuan more than that of company A. The average annual growth rate of company a's rent is calculated

Let the average growth rate be X
Then the total rent of company B in three years is 20 + 20 (1 + x) + 20 (1 + x) & 178; = 29 × 3 + 0.2
20*[1+(1+x)+(1+x)²]=87+0.2
20*(1+1+x+1+x²+2x)=87+0.2
20*(x²+3x+3)=87.2
x²+3x+3=4.36
x²+3x+9/4+3/4=4.36
(x+3/2)²+3/4=4.36
(x+3/2)²+0.75=4.36
(x+3/2)²=3.61
(x+3/2)²=1.9*1.9
x+1.5=1.9
x=0.4
Therefore, the average annual growth rate of rent of company B = 0.4 × 100% = 40%

When x takes what value, the fraction | X & # 178; - 16 | divided by X & # 178; - 8x + 16: 1 1 is meaningful; 2 is meaningless; 3 is zero

|x²-16|/(x²-8x+16)=|x²-16|/(x-4)²
(1) meaningful
(x-4)²≠0
x≠4
(2) meaningless
(x-4)²=0
x=4
(3) the value is zero
|x²-16|=0,(x-4)²≠0
So x = - 4
If you don't understand, I wish you a happy study!

X + 1 / 1 minus X-1 / x + 3 times x + 4x + 3 / x-2x + 1
You can find a piece of paper to write it down. The minus front is a fraction, and the plus front is also a fraction

1 / (x + 1) - X / (x ^ 2-1) + (x ^ 2-2x + 1) / (3x ^ 2 + 4x + 3) = - 1 / (x ^ 2-1) + (x-1) ^ 2 / (x + 1) (3x + 1) = 1 / (x + 1) * ((x-1) ^ 2 / (3x + 1) - 1 / (x-1)) = 1 / (x + 1) * (x ^ 2-5x) / (x-1) (3x + 1) = x (X-5) / ((x + 1) (x-1) (3x + 1)) do not know, right