
New Member
Word Problem for LinearQuadratic Systems
A square cupboard door contains four square panels. The border around each square panel has a uniform width of 4 cm. if the total area of the door excluding the panels is 720 cm^2, what are the dimensions of the door and each panel.
use substitution

Elite Member
How far have you gotten? You've drawn the picture and... then what?
Please reply with specifics. Thank you.
Eliz.

New Member
well the picture looks something like this:
and then i was thinking that one of the equations was x^2=720. but i think thats wrong. and i havent figured out the second one yet. cause i made the boxes inside equal to y and if each border was 4 cm i was thinking it would be 16...

Elite Member
What does "x" stand for? Or "y"?
Please include units in your description. Thank you.
Eliz.

New Member
oh yeah. i put my X= to one of the sides on the big square. and my Y=to one of the sides in the smaller square.

Elite Member
Thank you for the clarification (and my apologies for the delay in my reply, but I only just now got back home).
If the length of the side of an interior (and square) panel is "y", then the area of one panel is y<sup>2</sup> and the area of all four panels is 4y<sup>2</sup>.
Looking at the graph, the width of the door is 4 + y + 4 + y + 4 = 2y + 12. So is the height. So what is the area?
Now subtract the panel area from the total area, set equal to the given "door less panels" area, and solve.
I don't know what they mean by "use substitution". Sorry.
Eliz.
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