The length of a photograph is 3cm less than twice the width. the area is 54cm². find the dimentions of the photograph.

L=2w-3 

w(2w-3)=54

2w²- 3w-54=0

A= 2 , B= -3, C= -54

sub values into quadratic formula
 i attached picture of formula

Final  you will be given 2 answers 6 and -4.5. -4.5 is rejected since a negative value cannot represent length because that just doesn't make sense.

w=6

Check:
L=2w-3
=2(6)-3
=12-3
=9
  9*6=54

Therefore the dimensions of the photograph are 6 cm by 9 cm