решите уравнение:(3x+1)^2-100=0

( 3x + 1)² - 100 =0
(3x + 1)( 3x + 1) - 100 = 0
9x² + 6x + 1 - 100 = 0
9x² + 6x - 99 = 0
D = b² - 4ac = 6² - 4 × 9 × ( - 99) = 36 + 3564 = 3600 = 60²
x₁ = - 6 + 60 / 18 = 54/18 = 3
x₂ = - 6 - 60 / 18 = - 66/18 = - 3целых 2/3

(3х+1)²-100=0
9х²+6х+1-100=0
9х²+6х-99=0
D=36+3564=3600, √3600=60
х₁=-6+60/18=3
х₂=-6-60/18=-66/18=-11/3
Ответ: х₁=3 ;   х₂=-11/3