Question 98841: I have 2 questions I need help on understanding how you get the answer, such as 4x-8 or x^2+4x-21, etc.
A rectangle has length x+3 and width x-7. What is the area of the rectangle in terms of x.
A virus takes up a volume of 8.5x 10^-14 cubic centimeters. Calculate the estimated number of viruses in 28 cubic centimeters.
Thank you for your help.
Answer by malakumar_kos@yahoo.com(315)   (Show Source):
You can put this solution on YOUR website!
I have 2 questions I need help on understanding how you get the answer, such as 4x-8 or x^2+4x-21, etc.
A rectangle has length x+3 and width x-7. What is the area of the rectangle in terms of x.
A virus takes up a volume of 8.5x 10^-14 cubic centimeters. Calculate the estimated number of viruses in 28 cubic centimeters.
Thank you for your help.
1)4x-8 = 4(x-2)
2)x^2+4x-21 = x^2+7x-3x-21 = x(x+7)-3(x+7) = (x+7)(x-3)
3)Length of the rectangle L = (x+3)
width of the rectangle = B = (x-7)
Area of the rectangle = A = L.B
A = (x+3).(x-7)
= x^2-7x+3x-21
= x^2-4x-21.
4)8.5x10^-14 cc of volume is occupied by 1 virus
28 cc of volume is occupied by ? viruses
no of viruses = 28/8.5x10^-14
= 28x10^14/8.5
= 280x10^14/85
= 58x10^14/17
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