bonjour
Ensemble Def = [ 8 ; 10 ]
aire PNAM = x²
aire QCNR = ( 8 - x ) ( 10 - x ) = 80 - 8 x - 10 x + x² = x² - 18 x + 80
aire grisée = x² - 18 x + 80 + x² = 2 x² - 18 x + 80
aire totale = 10 x 8 = 80
2x² - 18 x + 80 ≥ 40
2x² - 18 x + 80 - 40 ≥ 0
2 x² - 18 x + 40 ≥ 0
Δ = ( - 18 )² - 4 ( 2 * 40 ) =324 - 320 = 4 = 2²
x 1 = ( 18 - 2 ) / 4 = 16 /4 = 4
x 2 = ( 18 + 2 ) /4 = 20 /4 = 5
