2007 Q7 (1 Viewer)

[DJel]

Could someone please explain to me why we can find the maximum of h (in part (ii)) by simply working it out like so?

3 - 0.4h > 0

- 0.4h > -3

h < 3/0.4

h < 7.5 m

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How does the discriminant (I'm assuming that's what we're doing), give you the maximum?

Thanks,

DJel.

 

[lost1]

well the question asks to show that: m = 2 (+or-) sqr(3 - 0.4h)

since 'm' is real, the discriminant 3 - 0.4h >= 0

thus h <= 7.5

that is, the value of h has to be less than or equal to 7.5.....ie. 7.5 is max possible height