Question

resolva equaçao :
a)9.(2n-5).(n+2)
b)2x-3=3x-1
    x-6    x-2

Answer 1

a)9.(2n-5).(n+2)
9.(2n² +4n -5n -10)
18n² +36n -45n -90
18n² -9n -90

2x-3 = 3x -1      multiplicando em cruz
x-6       x-2

(x-2) .(2x -3) = (x-6).(3x -1)
2x² -3x -4x +6 = 3x² -x -18x +6
2x² -3x² -3x -4x +x +18x +6 -6 =0   elimina +6-6
-x² -7x +19x=0
-x² +12x = .(-1)
x² -12x =0
x(x -12)=0
x=0
(x-12) =0
x-12=0
x= 12 

S{0 ; 12}

Answer 2

Resolva equação:
a) 9 . (2n - 5) . (n + 2)
(18n - 45) . (n + 2)
18n² + 36n - 45n - 90
18n² - 9n - 90

b) 2x - 3 = 3x - 1
    x - 6       x - 2
(2x - 3) . (x - 2) = (3x - 1) . (x - 6)
2x² - 4x - 3x + 6 = 3x² - 18x - x + 6
2x² - 7x + 6 = 3x² - 19x + 6
2x² - 3x² - 7x + 19x + 6 - 6 = 0
- x² + 12x = 0
a = - 1              b = 12                 c = 0
Δ = b² - 4 . a . c
Δ = 12² - 4 . (- 1) . 0
Δ = 144
x = b² ± √Δ
    --------------
       2 .a
x =  12 ± √144
      ----------------
          2 . 1
x =  12 ± 12
     ----------------
            2
x' =  12 + 12 
            2
x' = 24 ÷ 2
x' = 12

x" = 12 - 12 
           2
x" = 0 ÷ 2
x" = 0

Resposta: {12; 0}