The solution of (5x-90) / (3x + 90) = 2 / 3

The solution of (5x-90) / (3x + 90) = 2 / 3

(5x-90)/(3x+90)=2/3
15x-270=6x+180
15x-6x=270+180
9x=450
x=450÷9
x=50

3X/2 * 5X/2 - X * 3X/2=90,

[(13-0.5x)X3]/2+1/3x=12 (39-1.5x)/2+1/3x=12 39/2-3/4x+1/3x=12 (3/4-1/3)X=39/2-12 5/12X=15/2 X=18 [(13-0.

Under the microscope, the shape of a kind of cell in human body is approximately round. Its diameter is about 1.6 × 10 - 6 cubic meters
π is 3

π (1.6 △ 2) &# 178; △ the square of the magnification of the microscope

Under the microscope, the shape of a cell in the human body can be approximately seen as a circle, and its diameter is 0.00000159m
The approximate number obtained by keeping this data with three significant numbers is (expressed by scientific counting method)

1.56×10^-6

Under the microscope, a cell shape of human body can be approximately regarded as a circle with a radius of 7.8 × 10-7 cubic meters
(1) How many microns is 7.8 × 10-7 m (1 m = 10-6 m)?
(2) If a 100 yuan sheet is about 0.00009048 meters thick, how many of the above cells are connected end to end?

(1) 0.78 μ M
（2）57.36

Under the microscope, the cross section of a cell can be approximately seen as a circle with a radius of 7.8 x 10 to the - 7th power M
The cross-sectional area of this cell π≈ 3.14 can be expressed by scientific counting method

The cross-sectional area of cells is π× (7.85 × 10-7) 2 = 3.14 × 7.85 × 7.85 × 10-14 ≈
(according to the area formula s = π R2 of the circle, the cross-sectional area of the cell is calculated first, and then expressed by scientific notation. The general form of scientific notation is a × 10-N for positive numbers with absolute value less than 1. Different from the scientific notation of larger numbers, the negative exponential power is used, and the exponent is determined by the number of zeros in front of the first non-zero number from the left side of the original number.)
In this paper, the scientific notation is used to represent the smaller number. The general form is a × 10-N, where 1 ≤| a | 10. N is determined by the number of zeros in front of the first non-zero number from the left of the original number

Under the microscope, a cell shape of human body can be approximately seen as a circle, its radius is 7.8 × 10-7 meters, how many microns is it equivalent to? If a piece of 100 yuan RMB is about 0.00009 meters thick, how many of these cells are connected end to end?

7.8 × 10-7 M = 7.8 × 10-7 × 106 = 7.8 × 10-1 μ m; 7.8 × 10-7 M = 0.000 000 78 m, 0.000 09 △ (2 × 0.000 000 78) ≈ 58 cells. A: it is equivalent to 7.8 × 10-1 μ m, which is equivalent to the length of 58 cells

Under the microscope, the shape of a cell in the human body is approximately round, and its diameter is about 1.6 × 10 minus six square meters!

r=1/2d=1/2*1.6×10^-6=8×10^-7
s=πr^2=3*8×10^-7*8×10^-7=3×64×10^-14
=1.92×10^-12

A ring, outer circumference 12.56 decimeters, inner circumference 6.28 decimeters, the ring area is (), ring width () decimeters

What is the radius of the inner circle
2 = 1 (decimeter)
What is the radius of the outer circle
12.56 ﹣ 3.14 ﹣ 2 = 2 (decimeter)
Ring width
2-1 = 1 (decimeter)
What is the area of the ring
2 × 2 × 3.14-1 × 1 × 3.14 = 9.42 (square decimeter)

A simple method to multiply [99's square + 99] by 0.01

＝ 99﹙99＋1﹚×0.01
＝ 99×100×0.01
＝ 99