Can you help me solve this.

[Mel36]

A large McDonald's sign stands on the roof of a shopping center. The shape of one of the parabolas is modelled by the quadratic y=-x^2+8x-7 where both x and y are measured in metres. The complete sign is supported by a beam underneath the arches. What is the minimum length required for this beam?

 

[Otis]

Hello Mel. The exercise statement as posted is not complete. The model is a parabola that opens downward, but where is the beam located vertically? Is it located along the x-axis? Is it above or below the x-axis? Without a definition for what's meant by "the complete sign", we have to guess (which is not good). Asking for the minimum beam length implies that more than one size is possible, for the sign, too. Is that how you read it?

Please double-check that you have copied the exercise statement word-for-word (along with any instructions), exactly as you received it.

Also, finish the request you received to read the forum's guidelines. They explain the best way to ask for help here. Thanks!

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[topsquark]

You also need to specify how tall each part of the M is. The solution is different if the arch is to be 10m or, say, 100 m.

-Dan

 

[Mel36]

Hi All, I agree with you. The question is incomplete and more information is needed. Thanks so much for confirming what I already knew.
-M