The formula of practical problem Calculation formulas related to quadratic equation of one variable Just the formula! Examples are better! do somebody a favour

The formula of practical problem Calculation formulas related to quadratic equation of one variable Just the formula! Examples are better! do somebody a favour

Because option B contains fraction, it is not a quadratic equation of one variable; option C may be equal to 0, it is not necessarily a quadratic equation of one variable, because the value of a is uncertain; option D is a quadratic equation of one variable after simplification
According to the meaning of the solution of the equation, when x = 0, the left and right sides of the equation are equal. This problem is to find the value of m when x = 0. But at the same time, we must remember the precondition that when the equation is a quadratic equation of one variable, the coefficient of quadratic term is not 0, that is, m-2 ≠ 0
(1) to determine the root of one variable two equation, one method is to determine according to the definition of power, that is, the square of any number is non negative; the other method is to determine according to the value of "Δ ="
(1) the equation is in the form of (x + m) 2 = n (n ≥ 0), so it is easy to use the direct square method to solve the equation. In addition, if the coefficient of the first term is equal to zero, the direct square method is also used to solve the equation
(1) according to the calculation: Δ = = 20, its value is not a complete square, so it is not suitable to use the factorization method. Therefore, we can consider the collocation method or formula method to solve it
(2) the equation is first reduced to the general form x 2 - 3x = 0, and then analyzed. It is obvious that the factorization method is used
The above two questions belong to the same type, that is to say, they are all based on the relationship between the root and coefficient of quadratic equation with one variable to get the value of sum respectively. The first one is to use the idea of equation to get the value of letter coefficient K, and pay special attention to the test of the premise that quadratic equation with one variable must have real root. The second one is to transform the value of algebraic formula into the form of containing sum
This problem is about the average growth rate, and the equal relation is "the utilization rate will reach 60% in 2008". For the total amount of crop straw output each year, you can take it as 1, or you can set an unknown number, which will be naturally reduced in the solution

Engineering problem formula (application)
A garment factory processes a batch of work clothes. Each person in the cutting group can cut 15 pieces of work clothes every day, and each person in the sewing group can cut 5 pieces every day. There are 16 skilled workers who accept a batch of orders. How many people should be assigned to make the work clothes cut and sewn just match each other? (binary linear equations) * this question is correct

Let x cut and Y sew
1. 15x = 5Y
2、X+Y=16
X = 4, y = 12 from coco
That is, 4 people cut, 12 people sew

Solving equation (105-x) * 8 / 3 + 7x = 49
fast

Both sides * 3
105*8-8x+7x=147
x=840-147
x=693

The total amount of grain in warehouse A and warehouse B is 80 tons, of which 1 / 3 of the inventory in warehouse A is equal to 1 / 4 of that in warehouse B, and each warehouse stores grain

X+Y=80
x/3=y/4
x=240/7
y=320/7

How many circles can you draw on a piece of square paper with a side length of 18cm and a radius of 1.5cm?
2. The outer diameter of a bicycle wheel is 70cm, and a bridge is 1000m long. How many turns does the wheel have to turn when the bicycle passes through the bridge
Question 1 = 36

1.
If the radius of the garden is 1.5 cm, the diameter is 3 cm, so the meaning of the topic is equivalent to asking how many small squares with side length of 3 cm can be cut out
So it can be cut out
(18 / 3) ^ 2 = 36
two
The diameter of the wheel is 70 cm, and the distance of the wheel before one turn is 10 cm
πd=70π cm
So it takes a turn to cross the bridge
（1000*100 cm）/70π
=454.5,
Because we have to cross the bridge, we take 455 turns

0.8/0.25 （5.8*1.44+1.2*1.44）/1.2

0.8/0.25 =80/25=16/5=3.2
（5.8*1.44+1.2*1.44）/1.2.
=（5.8*+1.2)*1.44 /1.2
=7*1.44/1.2
=7*1.2
=8.4

Given that the sequence {BN} is an equal ratio sequence with the first term of - 4 and the common ratio of 2, and that the sequence {an} satisfies A1 = 60, an + 1-an = BN, then the general term formula an of the sequence {an}=______ ．

∵ {BN} is an equal ratio sequence with the first term of - 4 and the common ratio of 2, ∵ BN = − 4 · 2n − 1 = − 2n + 1, ∵ an + 1-an = BN = - 2n + 1. When n ≥ 2, a2-a1 = - 22, A3 − A2 = − 23 , an − an − 1 = − 2n, adding the above formulas, we can get an-a1 = - 22 (1 − 2n − 1) 1 − 2 = - 2n + 1 + 4, ｜ an = - 2n + 1 + 64, A1 = 60, which is suitable for the above formula, ｜ an = - 2n + 1 + 64, so the answer is: - 2n + 1 + 64

(1) It is easy to calculate 99 × (- 8) = (2) 42 × (- 19) = (10 × (- 21) =
(1) 99 × (- 8) = (2) 42 × (- 19) = (10 × (- 21) = simple calculation,

(99+5/16)x(-8) -42x(10+19/21)

Factorization A2 + B2 + c2-2ab + 2BC + 2Ac

2(a+b+c)-2(ab-bc-ac)=2(a+b+c-ab+bc+ac)

62-63 = 1. This equation is wrong. Move a number to make it correct. The sign cannot be changed

2 ^ 6-63 = 1 (the sixth power of 2). Besides, move a number to make it correct, and the sign can't be changed