Svar:
# Y = -5/8 (x-7/5) ^ 2 + 227/120 #
Forklaring:
# "ligningen af en parabola i" farve (blå) "vertex form" # er.
#COLOR (rød) (bar (ul (| farve (hvid) (2/2) farve (sort) (y = a (x-h) ^ 2 + k) farve (hvid) (2/2) |))) #
# "hvor" (h, k) "er koordinaterne til vertexet og en" # "
# "er en multiplikator" #
# "givet ligningen i standardformular" #
# • farve (hvid) (x) y = ax ^ 2 + bx + c farve (hvid) (x); a! = 0 #
# "så er krydsets x-koordinat" #
# • farve (hvid) (x) x_ (farve (rød) "toppunkt") = - b / (2a) #
# y = -5 / 8x ^ 2 + 7 / 4x + 2/3 "er i standardformular" #
# "med" a = -5 / 8, b = 7/4 "og" c = 2/3 "
#rArrx_ (farve (rød) "toppunkt") = - (7/4) / (- 5/4) = 7/5 #
# "erstat denne værdi i ligningen for y" #
#y_ (farve (rød) "toppunkt") = - 5/8 (7/5) ^ 2 + 7/4 (7/5) + 2/3 = 227/120 #
# rArry = -5 / 8 (x-7/5) ^ 2 + 227 / 120larrcolor (blå) "i vertex form" #
