Solve the equation x - (3x + 8) = 21 x + 5 / x = 120 A number plus 25% is three times 20. Find the number Four times more than a number, 10 is 150. Find this number It's a great reward. $_ $ $_ $ $_ $ $_ $ $_ $ $_ $ $_ $ $_ $ $_ $ $_$

Solve the equation x - (3x + 8) = 21 x + 5 / x = 120 A number plus 25% is three times 20. Find the number Four times more than a number, 10 is 150. Find this number It's a great reward. $_ $ $_ $ $_ $ $_ $ $_ $ $_ $ $_ $ $_ $ $_ $ $_$

1. If x-3x-8 = 21, x = - 29 / 2; if x-3x-8 = 21, x = ± root sign (3595) + 60
2. X + 25% x = 20x3 x = 60 divided by 1.25 x = 48
3、4x+10=150 x=(150-10)/4=35

First aid! The side area of a cone is exactly 4 times of its bottom area. Find the degree of the central angle of the sector corresponding to the expanded side area of the cone

Let R be the bottom radius and l be the generatrix,
We get π * r * l = 4, π * r * r = L = 4R, and we get n = 90 by using another formula of cone area (side expansion with center angle) n π L * L / 360 = π RL

1. Pour 120 liters of diesel into a cylindrical oil barrel with a bottom area of 25 square decimeters. What is the height of the oil level in the barrel
2. A cylindrical bucket has a volume of 24 cubic decimeters, an inner bottom area of 6 square decimeters, and holds 3 / 4 barrels of water. How high is the water surface?
3. The bottom radius of a cylinder is 2 decimeters, which is full of water. Pour the water into a 1.57 liter cup. How many cups can you pour?
To be clear and complete, it's better to use the comprehensive formula and write down the unit clearly,

1. Height = 120 △ 25 = 4.8 decimeters
2. Water height = 24 △ 6 × 3 / 4 = 3 decimeters
3.2 × 2 × 3.14 × 2.5 △ 1.57 = 20 cups

It is known that the solution set of the inequality x2-3x + a < 0 about X is (1.2) to find the solution set of the inequality ax squared minus 3x + 1 > 0

X & # 178; - 3x + A0 is 2x & # 178; - 3x + 1 > 0
(x-1)(2x-1)>0
x1
Therefore, the solution set of the inequality is (- ∞, 1 / 2) U (1, + ∞)
I wish you happy! Hope to help you, if you do not understand, please hi me, I wish learning progress_ ∩)O

As shown in the figure, the area of a square is 12 square centimeters. Find out the area of a circle

That is, side length multiplied by side length = 12
Side length equals radius
So the area of the circle is 3.14 times radius times radius = 3.14 times 12 = 37.68 square centimeters

We define ABCD = ad BC, for example = 2 × 5-3 × 4 = 10-12 = - 2. If x and y are integers and satisfy 1 < 1xy4

According to the definition, 1xy4 = 1 * 4-xy = 4-xy
one

Minus three is five sixths minus two. X = one half

-3-5/6-2x=1/2
2x=-3-5/6-1/2
2x=-3-5/6-1/2
2x=-13/3
x=-13/6

Geometry is too bad to understand the formula, chord length 4 meters, chord center to arc top 0.3 meters, find an arc length, urgent

Let R be the radius of the circle, then
(r-0.3)^2+2^2=r^2
That is, R ^ 2-0.6r + 0.09 + 4 = R ^ 2, so r = 4.09/0.6 = 6.81667m
Center angle = 2arctg (2 / 6.51667)
Arc length = 2R * arctg (2 / 6.51667) = 4.0597m

The sum of the arithmetic sequence is 160, the number of items is 11, and the tolerance is 3?

What's the problem? This is, the number of items is 11, these seven numbers?
Do it according to 11 items, and find the maximum of these 11 items
The middle term, the sixth term, is equal to the average = 160 / 11
Then item 11 = item 6 + tolerance * (11-6) = 160 / 11 + 3 × (11-6) = 325 / 11

2.5 times of a number is 1.8 less than 3.5 times of it. How much is the number

Let this number be X
3.5x-2.5x=1.8
x=1.8
So the number is 1.8