Solve the following equation and test 3x + 1 = - 2

Solve the following equation and test 3x + 1 = - 2

-2-1=-3
-3/3=-1
So x = - 1

Three and a half: (x + 3) = one sixth: 2 (solving the equation) fast

Three and a half: (x + 3) = one sixth: 2
7/2*2=1/6*（x+3)
(x+3)/6=7
x+3=6*7=42
x=42-3
x=39

- 19 and 8 / 9 × 3 = (please use simple calculation,)

- 19 and 8 / 9 × 3
=（-20+1/9）x3
=-20x3+1/9x3
=-60+1/3
=-59 and 2 / 3

Use n to represent any integer, use the algebraic expression containing n to represent: any odd number; 3 continuous even numbers
Use n to represent any integer, use the algebraic expression containing n to represent: any odd number; three continuous even numbers; numbers divisible by 3

2n+1
2n+（2n+2）+（2n+4）

Simple calculation of 5.6 × 1.01-0.56

5.6×1.01-0.56
=5.6*1.01-5.6*0.1
=5.6*(1.01-0.1)
=5.6*0.91
=5.096

The area ratio of the triangle to the square is 4:9. The side length of the square is 6cm. What is the height of the triangle?
The bottom of the triangle is six centimeters

The area of the triangle is 16
The bottom is 6cm
The height is 16 / 3 cm

23°30′=______ °         78.36°=______ °______ ′______ ″52°45′-32°46′=______ °______ ′18.3°+26°34′=______ °______ ′．

∵ 30 ′ = 0.5 °, ∵ 23 ° 30 ′ = 23.5 °; ∵ 0.36 ° = (0.36 × 60) ′ = 21.6 ′, 0.6 ′ = 36 ″, ∵ 78.36 ° = 78 ° 21 ′ 36 ″; 52 ° 45 ′ - 32 ° 46 ′ = 51 ° 105 ′ - 32 ° 46 ′ = 19 ° 59 ′; 18.3 ° + 26 ° 34 ′ = 18 ° 18 ′ + 26 ° 34 ′ = 44 ° 52 ′

Use a 6.28 decimeter long wire to form a square. If you use this wire to form a circle, what is the perimeter area of the circle?

The circumference is 6.28 decimeters
Circle radius 6.28 △ 3.14 △ 2 = 2 decimeters
Circular area 3.14 × 1 × 1 = 3.14 square decimeters

7.9/0.25 simple calculation

7.9÷0.25
=7.9×4÷（0.25×4）
=7.9×4÷1
=（8-0.1）×4
=8×4-0.1×4
=32-0.4
=31.6

As shown in the figure, the bottom BC of triangle ABC is 12.4, the height is 10.8, and E is the midpoint of AC. calculate the area of triangle Abe

ABC and Abe are the same height, Abe bottom is half of ABC, area is half. So the area is 1 / 2 * 1 / 2 * 12.4 * 10.8 = 33.48