Arthur D. answered 07/03/20
Forty Year Educator: Classroom, Summer School, Substitute, Tutor
R=(12+2x)(45-x) answer
R=540+90x-12x-2x^2
R=540+78x-2x^2
this is a parabola that opens downwards so it has a maximum point
this maximum occurs at (h,k), the vertex of the parabola
h=-b/2a
h=-78/-4
h=19.5 increases
x=19.5 increases of $2.00 each answer
2*19.5=$39 increase
$12+$39=$51.00 per m^2 (price of watermelon)
45-19.5=25.5 m^2 sold answer
check:
51*25.5=$1300.50 profit (12+2*19.5 and 45-19.5)
if x=19, you have 50*26=$1300 profit only, $0.50 less
if x=20, you have 52*25=$1300 profit only again
if x=18.50, you have 49*26.5=$1298.50
if x=20.5, you have 53*24.5=$1298.50
David S.
07/03/20