bonjour
A(x) = 15 x² - 22 x - 5
A (x) = - 5
15 x² - 22 x - 5 = - 5
15 x² - 22 x - 5 + 5 = 0
x ( 15 x - 22 ) = 0
x = 0 ou 22/15
A (x) = 0
15 x² - 22 x - 5 = 0
Δ = 484 - 4 ( 15 * - 5 ) = 484 + 300 = 784 = 28 ²
x 1 = ( 22 - 28 ) / 30 = - 6 /30 = - 1 /5
x 2 = ( 22 + 28 ) / 30 = 50/30 = 5/3
S ( - 1/5 ; 5/3 )
A (x) = 15 x²
15 x² - 22 x - 5 = 15 x²
15 x² - 15 x² - 22 x = 5
- 22 x = 5
x = - 5/22
A (x) = - 196/15
15 x² - 22 x - 5 = - 196/15
15 x² - 22 x = - 196/15 + 5
225 x² / 15 - 330 x /15 = - 196/15 + 75/15
225 x² - 330 x = - 121
225 x² - 330 x + 121 = 0
( 15 x - 11 )² = 0
x = 11/15
