How to find the area of a rectangle.?

Question

Here is the problem. I am pretty sure I know how to do this, but not positive. The answer for each should have variable(s) in it. not just an answer like "4".

a) There is a rectangle with a width of 5x and a length of x + 4. Find the area of the rectangle. 

b) Inside that rectangle, there is a smaller one. It has a width of 2x and a length of x + 12. Find the area.

c) Next, you are to subtract the area of the little rectangle from the area of the big rectangle. What do you get?

Thanks so much!

FreddyH · Accepted Answer

a)

area = length x width
area = 5x(x+4)
area = 5x^2 + 20x 


b)

area = 2x(x+12)
area = 2x^2 + 24x

c)

5x^2 + 20x - (2x^2 + 24x) = 
3x^2 - 4x

teja · Answer

a) area of the rectangle is 5x(x+4)

b) area of the rectangle is 2x(x+12)

c) 5x(x+4) - 2x(x+12)  = x[ 5(x+4) - 2( x+12)]

=> x[ 5x+20 - 2x-24 ]
=> x[ 3x-4 ]   or
=> 3x^2 - 4x

----ToRi---- - · Answer

a is 2(5x+x+4)    or 5x times  2  plus x + 4 times 2  so its 12x plus 4



b  is 2(2x +x+12)  6x plus 24 is the answer to this one and

c   6x plus 20

How to find the area of a rectangle.?

3 Answers