A simple and convenient method for the determination of trace elements

A simple and convenient method for the determination of trace elements

35.36÷（3.536×5）
=35.36÷3.536÷5
=10÷5
=2

Calculation: A / b (a-b) - B / a (a-b); (1 / A + 1 / b) △ A & # 178; + 2Ab + B & # 178; / A + B

a/b(a-b)-b/a(a-b)；=[a²(a-b)-b²(a-b)]/ab(a-b)=(a-b)²(a+b)/ab(a-b)=(a²-b²)/ab（1/a+1/b）÷a²+2ab+b²/a+b.=(a+b)ab × (a+b)/(a+b)²=ab

Fill in - 4, - 3, - 2, - 1,0,1,2,3,4 in the nine squares respectively, so that the three numbers in each row, the three numbers in each column and the three numbers in the diagonal are added together

3 -4 1
-2 0 2
-1 4 -3

A problem of binary linear equation in mathematics of grade one in junior high school
The scoring rules of football league matches: 3 points for winning one game, 1 point for drawing one game, and 0 point for losing one point. A certain team gets 6 points in four football league matches. How many games has the team won, drawn, and lost?

Let's win x field, draw y field and lose (4-x-y) field
Column equation: 3x + y = 6
So y = 6-3x > = 0, so x = 0
Because X and y are positive integers, X can take 0 or 1 or 2
When x = 0, y = 6
2. When x = 1, y = 3, so we won 1 game, drew 3 games and lost 0
3. When x = 2, y = 0, so we won 2 games, drew 0 Games and lost 2 games

26 divided by X is equal to y, 6 x minus y is equal to 5, how many are x and y?
X and y are not the result of integers. I'm so old. I've forgotten what I learned

From the meaning of the title,
26/x=y+6,
x-y=5
The process of solving the equation is as follows
26/x=y+6,26=xy+6x ①
x-y=5,x=5+y ②
Substitute (2) for (1),
26=5y+y²+30+6y
The solution is Y1 = (- 11 + √ 105) / 2, y2 = (- 11 - √ 105) / 2
They are substituted into 2,
x1=（-1+√105）/2,x2=（-1-√105）/2
Ψ X1 = (- 1 + √ 105) / 2, Y1 = (- 11 + √ 105) / 2 or x2 = (- 1 - √ 105) / 2, y2 = (- 11 - √ 105) / 2
(wrong column upstairs)

No matter what the value of X is, the value of the algebraic formula 2x ^ 4-4x ^ 2-1 is always greater than that of x ^ 4-2x ^ 2-4

(2x^4-4x^2-1)-(x^4-2x^2-4)
=x^4-2x^2+3
=(x^2-1)^2+2
Because x ^ 2 is greater than or equal to 0, (x ^ 2-1) ^ 2 is greater than or equal to 0
That is, (x ^ 2-1) ^ 2 + 2 is greater than or equal to 2
That is, (2x ^ 4-4x ^ 2-1) - (x ^ 4-2x ^ 2-4) is greater than or equal to 2
So the value of the algebraic formula 2x ^ 4-4x ^ 2-1 is always greater than the value of x ^ 4-2x ^ 2-4

1. It is known that 1 * 3 = 1 * 2 * 3, 4 * 5 = 4 * 5 * 6 * 7 * 8, please calculate 6 * 4 of 3 * 4 2. If a △ B = 5a-4b, X △ (5 △ 2) = 12, calculate X
1. It is known that 1 * 3 = 1 * 2 * 3, 4 * 5 = 4 * 5 * 6 * 7 * 8, please calculate 6 * 4 of 3 * 4
2. If a △ B = 5a-4b and X △ 5 △ 2 = 12, find X

1.3 6 out of 4 = 4 * 5 * 6 / (3 * 4) = 10
2.X△（5△2）= X△（5*5-4*2) = X△21 = 5X - 17*4 = 5X - 68= 12
5X = 80
X = 16

The length of the radius of the circumscribed circle of the triangle with three sides of 6cm, 8cm and 10cm is______ cm．

∵ the center of the circumcircle of a right triangle is the middle point of the hypotenuse, which is the longest side of the right triangle, ∵ the radius of the triangle circumcircle = 12 × 10 = 5cm, ∵ the radius of the triangle circumcircle is equal to 5cm

It is known that the solution of the equation KX = 4-x about X is a positive integer

kx=4-x
(k+1)x=4
Because x > 0 and is an integer
So K + 1 > 0
k>-1
So k = O, 1,4

The perimeter of a semicircular flowerbed is 20.56 meters. How many square meters is its area

If the radius of the flower bed is r, then there is
2r+3.14r=20.56
5.14r=20.56
r=4
Then the area s = 3.14r ^ 2 / 2
=25.12 (M2)
A: the area is 25.12 square meters
Expression
3.14×[20.56÷（2+3.14）]^2÷2
=25.12 (M2)