How to look at the temperature? For example, according to the weather forecast, it's - 13 degrees in XX city. How cold is it? For example, it's 20 degrees. How to look at the temperature forecast

How to look at the temperature? For example, according to the weather forecast, it's - 13 degrees in XX city. How cold is it? For example, it's 20 degrees. How to look at the temperature forecast

-13 degrees is the feeling in winter, you need to wear cotton padded jacket, thick coat, snow and ice, 20 degrees is the feeling in spring and summer, you can wear short sleeve

Given that x = 3, y = 2 are the solutions of the system of equations {(M + n) X-my = 9, MX + NY = 13, find the solutions of M and n

Substituting x = 3 and y = 2 into two equations respectively, we get
3(m+n)-2m=9 (3)
3m+2n=13 (4)
From (3)
m+3n=9 (5)
(5) 3 - (4)
7n=14
∴n=2
Substituting n = 2 into (5) yields
m+6=9
∴m=3
∴m=3
n=2

(1) Reduction ratio (2) 5:6:9:4 (3) 75 cm: (4) 3:4 hours: 1
(1) 1 x 2-1 x 3 = 1
(2) 8 1 / 3 x = 1 2 / 3
(3) 4X of 9-1 of 8 = 1 of 24

(1) Simplification ratio
(2) 5 / 6:4 / 9 = 5 / 6 × 9 / 4 = 15 / 8 = 15:8
(3) 75 cm: 4 / 5 m 75 cm: 80 cm = 15:16
(4) 3 / 4 hours: 25 minutes = 45 minutes: 25 minutes = 9:5
solve equations,
(1) 1 x 2-1 x 3 = 1
x/6=1
x=6
(2) 8 1 / 3 x = 1 2 / 3
x=25/3÷5/3
x=5
(3) 4X of 9-1 of 8 = 1 of 24
4/9x=1/24+1/8
4/9x=1/6
x=1/6×9/4
x=3/8

How to deal with the denominator of a linear equation with one variable being a decimal

It's the same as integers
For example, 3.5x-2 = 5
transposition
3.5x=5+2=7
x=7÷3.5
x=2
To remove the denominator is to multiply both sides of the equation by the common denominator
such as
3x/5+2/3=3
The least common multiple of 3 and 5 is 15
So multiply both sides by 15
15×(3/5)x+15×(2/3)=15×3
9x+10=45
9x=45-10=35
x=35÷9
x=35/9

Simple calculation of 8 × 55 + 0.8 × 11

There's a big mistake upstairs. Look at the standard process
Original formula = 11x5x8 + 0.8x11
=11(40+0.8)
=448.8
Easy!
reference material:
My brain
Hope to adopt

The midpoint of the line segment cut by the circle x ^ 2 + y ^ 2-2x-2y-7 = 0 is_______ .

x²+y²-2x-2y-6=0
(x-1)²+(y-1)²=9
The coordinates of the center of the circle are o (1,1)
Let the midpoint of the cut chord be a
Then OA vertical line x + Y-1 = 0
So the slope of OA is 1
The equation of OA is y = X
Coupled equations
x+y-1=0
y=x
The solution is x = y = 1 / 2
The midpoint coordinates are (1 / 2,1 / 2)

Division of rational numbers in mathematics problems of grade one
It is verified by scientific experiments that the air temperature will decrease by about 0.6 ℃ for every 100 meters increase in height. The temperature of the high altitude balloon measured today is - 10 ℃ and the ground temperature is 5 ℃. Try to find the height of the balloon
Best in an hour!

-10 ℃ - 5 ℃ = 15 ℃ / 15 ℃ / 0.6 ℃ × 100 = 2500 m

As shown in the figure, in △ ABC, e is a point on BC, EC = 2be, and point D is the midpoint of AC. suppose that the areas of △ ABC, △ ADF, and △ bef are s △ ABC, s △ ADF, and s △ bef respectively, and s △ ABC = 12, then s △ adf-s △ bef=______ ．

∵ point D is the midpoint of AC, ∵ ad = 12ac, ∵ s △ ABC = 12, ∵ s △ abd = 12S △ ABC = 12 × 12 = 6. ∵ EC = 2be, s △ ABC = 12, ∵ s △ Abe = 13s △ ABC = 13 × 12 = 4, ∵ s △ abd-s △ Abe = (s △ ADF + s △ ABF) - (s △ ABF + s △ BEF) = s △ adf-s △ bef, i.e. s △ adf-s △ bef = s △ abd-s △ Abe = 6-4 = 2

What is the quotient of the sum of 1 / 5 and its reciprocal divided by 0.2

（1/5+1÷1/5）÷0.2
=5.2÷0.2
=26

-x. 2X ^ 2, - 3x ^ 3, 4x ^ 2. What is the nth number

N is odd
an=-n*x^n
N is even
an=n*x^2