Question

x dois +x ( 2x-45)=0

Answer 1

x^2 +x ( 2x - 45)= 0

x^2 + 2x² - 45x = 0 ==> 3x² - 45x = 0

3x(x - 15) = 0

3x1 = 0 ==> x1 = 0

x2 - 15 = 0 ==> x2 = 15

Answer 2

x^2 + x.(2x - 45) = 0
x^2 + 2x^2 - 45x = 0
3x^2 - 45x = 0

a = 3
b = - 45
c = 0

Delta = b^2 - 4.a.c
Delta = (- 45)^2 - 4.3.0
Delta = 2025 - 0
Delta = 2025

x = - b +- VDelta/2.a
x = - (- 45) +- V2025/2.3
x = 45 +- 45/6

x' = 45 - 45/6
x' = 0/6
x' = 0

x" = 45 + 45/6
x" = 90/6
x" = 15

S = { 0, 5 }