The diameter of a human red blood cell is 0.000009 m. The diameter of a cold virus is 0.00000003 m Approximately how many times as large is the diameter of a red blood cell as the diameter of a cold virus? A :3⋅10^-14 B:3⋅10 ^−2 C :3⋅10 ^1 D ;3⋅10 ^2

D. 3*10^2

Step-by-step explanation:

Given the diameter of human red blood cell =  0.000009 m

diameter of a cold virus = 0.00000003 m

To know how many times as large is the diameter of a red blood cell as the diameter of a cold virus, we will take the ratio of the diameter of human red blood cell to that of a cold virus as shown;

diameter of human red blood cell/diameter of a cold virus = 0.000009 m/0.00000003 m

= 9*10^-6/3*10^-8

= 9/3 * 10^-6-(-8)

= 3 * 10^(-6+8)

= 3*10^2

Hence the diameter of a red blood cell is 3*10^2 larger than that of the cold virus

X² - 14x + 45 = 0

Complete the square of (x² -14x + ??²), the (??)² will be  the missing square.

We know 14x = (2.x).(??) → then ?? = 14/2 and ?? = 7 or (??)² = 49
Then x² - 14.x  + 49 - 49 +45
(x² - 14.x  + 49) -49 + 54

(x-7)² -4 = 0

(x-7)² = 4

√(x-7)² = √4
(x-7) = + or - 2

and x = +2 +7 = 9  or x = -2 +7 =5, then the solutions are x' = 9 & x" = 5