X-3/7=（3X+2-53）/15

X-3/7=（3X+2-53）/15

x=67/14

(1) - 2x ^ 2 - [(- 13X) - 4 (3x ^ 2-4x) + 3x ^ 2], where x = - 4
(2) 2 (- A ^ 2B + 3AB ^ 2) - 4 (AB ^ 2 + 3A ^ 2b) - 2 (AB ^ 2-2a ^ 2b) where a = - 2, B = 1 / 4

(1) After simplification, it is 1 / 2x ^ 2 + 10x, and the result is - 32
(2) After reduction, it is - 10A ^ 2B, and the result is - 10

3x & # 178; + 13X + 3 = 0, find x,

The formula x = (- 13 ± 133) / 6 is obtained by substituting the formula x = (- 13 ± 133) / 6

15 / 16 is equal to 1 / a plus 1 / B plus 1 / C plus 1 / d. find the sum of four numbers ABCD

It's half and a quarter and an eighth and a sixteenth
The sum of ABCD is 30

Roll a sector iron sheet with a radius of 20 cm and a center angle of 144 degrees into a cone. What is the bottom radius of the cone?

Shituo 2000,
Bottom perimeter: 2 × 3.14 × 20 × 144 / 360 = 50.24 (CM)
Bottom radius: 50.24 △ 3.14 △ 2 = 8 (CM)

In the arithmetic sequence {an}, if A1, A2 and A4 are exactly proportional sequence, then the value of a1a4 is______ ．

If d = 0, then A1 = A4, a1a4 = 1; if D ≠ 0, then A1 = D, A4 = a1 + 3D = 4A1, a1a4 = 14. So the answer is: 1 or 14

No more than 30 words in English speech

Jinan,the City of Springs is popular among tourists for its many springs.Jinan As everyone knows, English is very important

The vertex a of △ ABC is fixed, the length of the opposite side BC of point a is 2a, the length of the high side BC is B, and the side BC moves along a fixed line to find the outer center of △ ABC
Finding the outer center of △ ABC
The trajectory equation of the system

Take a as the origin, the height on the side of BC as the x-axis, and the straight line where BC is located as x = B, establish a rectangular coordinate system. Let the outer center of △ ABC be p (x, y), and p be on the vertical bisector of BC, then the coordinates of B and C are (x + A, 0), (x-a, 0) respectively
And: ∥ AP ∥ = ∥ BP ∥
√(x^2+y^2)=√[a^2+(y-b)^2]
That is, the trajectory of point P is: x ^ 2 = - 2by + A ^ 2-B ^ 2

The circumference of the bottom surface of a cuboid is 32 cm, the height is 8 cm, and the volume is several cubic decimeters?

If your question is: the bottom of a cuboid is a square, the circumference is 32 cm, the height is 8 cm, and the volume is several cubic decimeters?
Formula: (32 △ 4) × (32 △ 4) × 8 = 512 (cm3)
512 cubic centimeter = 0.512 cubic decimeter
If you think your topic is correct, you can count it, but you can't get a definite value

Known π / 2

Because of π / 2