SOLUTION: 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 rectang

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
RELATED QUESTIONS
I really need help understanding and linear equations such as ex.) -8<2/3x-4<10 or... (answered by lwsshak3)

i need help with factoring questions such as {{{ x^3 - x^2 - 4x + 4 = 0... (answered by luckycarebear4)

I need help on Multiplying Binomials. How do you solve the following questions? (3m... (answered by stanbon)

I'm not sure what type of equation this is, but I need help on how the answer was found. (answered by drk)

hello I need help understanding this equation and also how to get the answer too!... (answered by mananth)

I need to solve the equation {{{x^4+4x^3+2x^2=0}}} for all real numbers. This is what i... (answered by rapaljer)

Please help me. I need to solve the following systems of equations by graphing and then... (answered by josgarithmetic)

How do you do them because the question i have on a worksheet which is,4y^2=25-4x^2,... (answered by neta)

A rectangle is inscribed in a circle of radius 6 (see the figure). Let P=(x,y) be... (answered by Edwin McCravy)