Simple formula of 0.8 * 72.4 * 12.5

Simple formula of 0.8 * 72.4 * 12.5

0.8×72.4×12.5
=0.8×12.5×72.4
=10×72.4
=724

3,5,8,12 general term formula

A1=3
A2=A1+2
A3=A2+3
┇
An=An-1+n
An = 3 + 2 + 3 + ┈ + n = 3 + (n + 2) (n-1) / 2 = (n & sup2; + N + 4) / 2

(1 / 4 △ 12.5% - 0.8) × 40% is still a simple formula

Original formula = 2 × 40% - 0.8 × 40% = 0.8-0.32 = 0.48

Given p (1, y), q (x, 2), if PQ / / X axis and segment PQ = 3, then x =, y =

∵PQ//x
∴y=2
∵PQ=3
∴|1-x|=3
X = - 2 or x = 4

Some common conclusions and proof methods of function symmetry and periodicity

Periodic function means that the value of function changes periodically with the change of independent variable. Sine and cosine functions are periodic functions. The expression is f (x + T) = f (x) (x takes any value). If a function can find t satisfying this condition, then the function is called periodic function. The period is t. f (1 + x) = f (1-x) (1 + x) + (1-x)

Let the equation of line l be (a + 1) x + y + 2-A = 0 (a ∈ R). If the intercept of line L on two coordinate axes is equal, the equation of line L is obtained

Let x = 0 get y = A-2, that is, the intercept of a straight line on the Y axis is A-2, and the intercept of L on the two axes is equal, let y = 0 get x = a − 2A + 1, let y = 0 get x = a − 2A + 1, let y = 0 get x = a − 2A + 1, let A-2 = a − 2A + 1, and solve the equation of a = 2 or a = 0 ℅ l as follows: 3x + y = 0 or x + y + 2 = 0

How can 9.9 * 3.4 + 0.34 be easily calculated?

9.9*3.4+0.34
= 9.9*3.4+3.4*0.1
=（9.9+0.1）*3.4
=10*3.4
=34

If the line y = KX + B is parallel to the line y = 2 − X3 and intersects with the line y = − 2x + 13 at the same point on the Y axis, the analytical expression of the line is______ ．

If the line y = KX + B is parallel to the line y = 2 − X3, then k = - 13; if the line y = KX + B and the line y = − 2x + 13 intersect at the same point on the Y axis, then B = - 13

It is known that for any n ∈ n *, the point (n, Sn) is on the image of function y = BX (superscript) + R
Supplement (b > 0, B ≠ 1, B, R are constants)
(1) The value of R
(2) When B = 2, note BN = (n + 1) / 4An (n ∈ n *), and find the first n terms and TN of the sequence {BN}

In physics, the amount of charge of a charge is 2 * (negative octave of 10). Can that explain that it has a positive charge?

In general, in order to explain the electrical property, the plus and minus sign will be added in the calculation topic. The amount of charge mentioned here is only the amount of charge, but it does not indicate the positive and negative charge