1 / 4x plus 1 / 3x = 5 / 18, the process is necessary

1 / 4x plus 1 / 3x = 5 / 18, the process is necessary

1 / 4x plus 1 / 3x = 5 / 18
Multiply both sides by 36
9x+12x=10
21x=10
x=10/21

In the arithmetic sequence {an}, if an ≠ 0, A1, A3 and A4 are equal ratio sequence, and the common ratio is Q, then Q=______ ．

Let the tolerance of the arithmetic sequence {an} be D, ∵ A1, A3, A4 be a proportional sequence, ∵ (a1 + 2D) 2 = A1 (a1 + 3D), the solution is d = 0 or D = - 14a1, when d = 0, the common ratio q = 1, when D = - 14a1, the common ratio q = a3a1 = 14, so the answer is: 1 or 14

Self introduction speech of junior one
Next week is our school English week, the teacher asked me to write an English self introduction speech
requirement:
1. Grade one of junior high school
2. 100 ~ 200 words
3. Novel, not always I, my or something
Chinese Name: Liu Guangcai English Name: Michael, 13 years old
Give me an answer tonight!
Shanexing this, but your format is too single, all I my, so it's not adopted

Glad to see you! My name is beryl, I am a nice girl. I am thirteen years old. There are three poeple in my family, my father, my mother and I. I like reading and making friends with other people very much. I also enjoy speaking English. My favorite sport is ping-pong.

A of the triangle ABC is fixed, the length of BC is 2a, the height of BC is B, BC moves along a straight line, and the trajectory equation of the outer center of the triangle is obtained

Take BC as X axis and high line as y axis to establish rectangular coordinate system, then point a (0, b), set outer center (x, y), point B (x1,0), point C (x1-2a,0)
The distance from the center of a circle to three points is equal
x^2+（y-b）^2=y^2+(x-x1)^2=y^2+(x-x1+2a)^2
The result is: 2by = x ^ 2 + B ^ 2-A ^ 2

There is a cuboid, its bottom circumference is 8 cm, the side view is also a square, find the volume of the cuboid

Length 2, width 2, height 8, so volume 2x2x8 = 32

If cos (π - a) = 4 / 5 and Tana > 0, then cos (π + a)=

cos(π+a)
=cos(2π-π+a)
=cos(-π+a)
=cos(π-a)
=4/5

Given that m and N are two real roots of the equation x2-2x-1 = 0, the value of the algebraic formula 3m2-n2-8m + 1 is ()
A.9 B.7 C.1 D.-1
I want to know why,

x²-2x-1=0
x²-2x=1
x²-2x+1=2
（x-1）²=2
X-1 = radical 2 X-1 = negative radical 2
M = 1 + radical 2 n = 1 + negative radical 2
Substitution evaluation
Get 1

If the definition field of odd function f (x) = SiNx + C is [a, b], then a + B + C=______ ．

∵ the definition domain of odd function f (x) = SiNx + C is [a, b], ∵ a + B = 0, and f (0) = sin0 + C = 0. If C = 0, then a + B + C = 0, so the answer is: 0

The solution of the equation (X-6) × 1.6 = 8

x-6=8÷1.6

The major axis is on the y-axis, the distance between the guide lines is 36, and the distance between a point on the ellipse and the two focal points is 9 and 15 respectively

The directrix of the ellipse is y = ± a ^ 2 / C, so 2A ^ 2 / C = 36, a ^ 2 = 18C
And: 2A = 9 + 15, then, a = 12, C = 8, a ^ 2 = 144, B ^ 2 = 80
The ellipse is: x ^ 2 / 80 + y ^ 2 / 144 = 1