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If-3-x-4-2-y-5-4-z-10-find-the-greatest-value-of-w-z-xy-




Question Number 97438 by john santu last updated on 08/Jun/20
If −3≤x≤4, −2≤y≤5, 4≤z≤10  , find the greatest  value of w = z−xy
If3x4,2y5,4z10,findthegreatestvalueofw=zxy
Commented by bemath last updated on 08/Jun/20
for xy = −15 and z = 10  then max of w = z−xy = 10−(−15)=25
forxy=15andz=10thenmaxofw=zxy=10(15)=25
Answered by 1549442205 last updated on 08/Jun/20
From the hypothesis  { ((−3≤x≤4)),((−2≤y≤5)) :} we get  20≥xy≥−15⇒−20≤−xy≤15(1)which  by the combine to 4≤z≤10 (2),plus two same dimension inequalities   (1)and (2) we obtain that −16≤z−xy≤25.This means  z−xy_(min) =−16 when (x;y;z)=(4;5;4)and  z−xy_(max) =25 when (x;y;z)=(−3;5;10)
Fromthehypothesis{3x42y5weget20xy1520xy15(1)whichbythecombineto4z10(2),plustwosamedimensioninequalities(1)and(2)weobtainthat16zxy25.Thismeanszxymin=16when(x;y;z)=(4;5;4)andzxymax=25when(x;y;z)=(3;5;10)

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