Calculation: (1) LG25 + lg2lg50 + (LG2) 2 (2) 813 + (12) − 2 + (27-1 + 16-2) 0 + 416

Calculation: (1) LG25 + lg2lg50 + (LG2) 2 (2) 813 + (12) − 2 + (27-1 + 16-2) 0 + 416

(1) The original formula = 2lg5 + LG2 (1 + lg5) + lg22 = 2lg5 + LG2 + LG2 (lg5 + LG2) = 2 (lg5 + LG2) = 2. (2) the original formula = (23) 13 + (2-1) - 2 + 1 + 2 = 2 + 2 + 3 = 7

The square of LG2 plus LG2 times LG50 plus LG25

Original formula = LG2 (LG2 + LG50) + 2lg5
=lg2(lg2+lg5+lg10)+ 2lg5
=lg2(1+1)+ 2lg5
=2(lg2+lg5)=2

On the two equations (lgx) &# 178; - (LG2 + Lg3) lgx + LG2 · Lg3 = 0 of X are x1, X2, find the value of x1 · x2

(lgx)²-(lg2+lg3)lgx+lg2·lg3=0
（lgx-lg2）（lgx-lg3）=0
lgx-lg2=0,x1=2
lgx-lg3=0,x2=3
x1·x2=2*3=6

Make a straight line through a vertex a of the parallelogram ABCD, intersect the diagonal BD, the extension of the edge BC and the edge CD at the point EFG, and prove EA2 = EF * eg
In triangle ABC, de ∥ BC, EF ∥ AB judge the character of quadrilateral bdef, and prove BD / AB = CF / BC

From the triangle AEB is similar to the triangle GED, we know AE / EG = be / De, from the triangle AED is similar to the triangle Feb, we know EF / AE = be / De, so AE / EG = EF / AE, that is EA2 = EF * eg

A man-made earth satellite runs in a circular orbit with an orbit radius of 6.8 × 103km and a period of 5.6 × 103s. We try to estimate the mass of the earth g = 6.67 × 10-11n · m2 / kg2 from these data

According to the universal gravitation, the centripetal force gmmr2 = MR (2 π T) 2, M = 4 π 2r3gt2 = 6 × 1024kg

What is the formula for calculating the volume, surface area, side area and bottom area of a cone and the circumference of its base?

Volume formula of cone: bottom area x Height x 1 / 3
Cone surface area formula: cone diameter x3.14x height X1 / 3
Formula of cone side area: diameter x height divided by 2
Formula of cone bottom area: square of cone radius x3.14
Bottom circumference formula: cone diameter x3.14

The circumference of the rectangle is 130 cm. If the length is increased by 2 / 7 and the width is decreased by 1 / 3, we can get a new rectangle with the same circumference. What is the length and width of the original rectangle
Distribution formula

Because a key point is that the perimeter remains unchanged, the length of length increase is equal to the length of width decrease. Let length be a and width be B, so: 2 / 7a = 1 / 3b, a = 7 / 6B ① According to the formula: perimeter = (length + width) * 2 (a + b) * 2 = 130, a + B = 65 ② Based on the above two formulas, we get: 7 / 6B + B = 65

Use the rounding method to get the approximate value, keep four significant numbers of 0.0031428, and express it as 0.0031428 by scientific notation__________ If it is accurate to ten thousandth place, it can be expressed as__________

3.143X10^3
3.1428X10^3

It takes 80 seconds for a train to pass a 456 meter long bridge and 77 seconds for a train to pass a 399 meter long tunnel at the same speed

If the train speed is x m / s and the length is Y M, then
80X=456+Y
77X=399+Y
The velocity is 19 m / s, the speed is 68.4 km / h and the length is 1064 M

If the length and width of a rectangle are increased by 5 cm, the area will be increased by 100 square cm. What is the circumference of the rectangle
in a rush

(x + 5) * (y + 5) - xy = 100; 5 (x + y) + 25 = 100; X + y = 15; therefore, the perimeter is 30;