Question

(x mais 5) (x menos 6) igual 51 menos x

Answer 1

(x+5) * (x-6) = 51-x
x² - 6x + 5x - 30 = 51 - x
x² - x - 30 = 51 - x
x² - x + x - 30 - 51 = 0
x² - 81 = 0
a= 1, b= 0, c= -81

∆= b² -4.a.c
∆= 0² -4.1.(-81)
∆= 324

x= -b±√∆ /2.a

x'= 0+18/2.1
x'= 18/2
x'= 9

x"= 0-18/2
x"= -9

S= {9, -9}

Bons estudos! :)