Question

Oblicz x oraz y, jeśli:

y = + 6x + 9 oraz y = 100

Answer 1

y=x²+6x+9

(x+3)²=y

x=-3

y=9-18+9

y=-18

Answer 2

100 = x^2 + 6x + 9

x^2 + 6x - 91 = 0

delta = 6^2 - 4*1*(-91) = 36 + 364 = 400

p (delty) = p (400) = 20

x1 = [ -6 - 20]/2 = -26/2 = - 13

x2 = [ -6 + 20]/2 = 14/2 = 7

y = 100  , więc nie trzeba obliczać:

Odp.

Mamy: ( -13; 100)  i  ( 7; 100)

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