Question

An envelope is 4 cm longer than it is wide. the area is 96 square centimeters. find the length and width.

Answer 1

So, L*W=A Because it is 4 cm longer, L=W+4 Because the area is 96, LW=96 Substitute to get W(W+4)=96 Multiply it out. W^2+4W-96=0 By solving the quadratic, W+12(W-8)=0 so either W+12 or W-8 is zero. The width must be positive, so the width is 8. Therefore the length is 12. 

  Hope this helps.