SOLUTION: a rectanlge has an area of 50cm2, if its length is twice its width, find the perimeter

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Question 857279: a rectanlge has an area of 50cm2, if its length is twice its width, find the perimeter
Answer by Menjax(62) About Me  (Show Source):
You can put this solution on YOUR website!
call the length x
call the width y
x*y = 50cm2 equation 1
x/2 = y equation 2
sub equation 2 into equation 1
x(x/2) = 50
x2/2-50=0
factorise (dots/dops)
(x/sqrt(2) - 5sqrt(2))(x/sqrt(2) + 5sqrt(2))=0
null factor law:
x = 5sqrt(2)*sqrt(2) or -5sqrt(2)*sqrt(2)
x = 10 or -10
but length cant be negative so it cant be -10
so x = 10cm and y=5cm