0.4:2.5 = x: 1.75

0.4:2.5 = x: 1.75

0.4：2.5=X：1.75
2.5X=1.75×0.4
2.5X=0.7
X=0.7÷2.5
X=2.8
I wish you a happy study!

Given that K is an integer, the equation (K + 2) x = 3 about X has a positive integer solution, then the value of K is

First of all, consider the special case, when K + 2 = 0, it does not hold for any x, so k = - 2 does not meet the condition
When K + 2 is not equal to 0
x=3/(k+2)
Obviously, when K + 2 > 3, x0 (because it is a positive integer solution)
So 0

When k takes what value, the solution of the equation 1 / 2kx-5 / 3 = 1 / 2 (X-5 / 3) about X is a positive integer

1/2kx-1/2x=-5/3-5/6
1/2（k-1）x=5/6
（k-1）x=5/3
x=5/3（k-1）
When k = 4 / 3, x = 1:; when k = 8 / 5, x = 5

Know the angle of arc 50 degrees, chord length 62, how to find the radius of the circle?

We know a / Sina = B / SINB = C / sinc from sine theorem
Radius of circle / sinc = chord / sin50
∠C=65
So the radius of the circle is 62 / sin50 × sin65

Reasoning of the formula for finding the last, first and tolerance of arithmetic sequence
Talk about the process of reasoning out the formulas of arithmetic sequence. How this formula was derived should be explained in detail.

It's all in there
The first item doesn't need a formula, does it?
Because it is an arithmetic sequence, the differences are equal, and this difference is called tolerance
It's the latter minus the former
Last term formula an = a1 + D (n-1)
That's how I understand it
The tolerance knows that this number is composed of the first item and countless tolerances
A larger tolerance means a larger D, and an N-term means n-1 D
So an = a1 + D (n-1)

3 / 16 of a certain number is equivalent to 3 times of 5 / 8. Find a certain number and use the equation to solve it

Some number x
Equation 3 / 16 * x = 5 / 8 * 3
Solve the equation and get 3 / 16 * x = 15 / 8
x=10
A very simple problem of solving equations

English translation
Write an article about your hobbies,

Hobbies
I think everyone has some hobbies.Some boys in my school like playing basketball and football.Some girls like shopping.My mother likes watching TV.My father likes fishing.And I like swimming very much.I oten have a good time palying in the water.

What is the ratio of 1 / 4 to 1 / 8 to the simplest integer?

5 to 36

Solving equation (10-x) = 10x

(10-x) = 10x 100-20x + x = 10x x x-30x + 100 = 0 x-30x + 225 = 125 (X-15) = 125 X-15 = ± 5 √ 5 x = 15 ± 5 √ 5 x ≥ 0 is obtained from (10-x) = 10x, so x = 15-5 √ 5

A cuboid has a surface area of 100 square centimeters, a bottom area of 18 square centimeters, and a bottom perimeter of 20 centimeters. What is the cuboid's volume in cubic centimeters

The side area of a cuboid
=The surface area of a cuboid - the area of the top and bottom surfaces
=100-18*2、
=100-36、
=64 square centimeters
The height of cuboid
=Side area of the box / perimeter of the bottom of the box
=64/20、
=3.2 cm
The volume of the cuboid
=The bottom area of the cuboid * the height of the cuboid
=18*3.2|
=57.6 cm3