Explications étape par étape
1. 2x + 1 / 1 - 3x = 1/2
Égalités de produits en croix :
2 * ( 2x + 1 ) = 1 * ( 1 - 3x )
4x + 2 = 1 - 3x
4x + 3x + 2 = 1 - 3x + 3x
7x + 2 - 2 = 1 - 2
7x = - 1
x = - 1/7
2. a. ( x + 1 )^2
= ( x + 1 )( x + 1 )
= x^2 + x + x + 1
= x^2 + 2x + 1
( 2 - x )^2
= ( 2 - x )( 2 - x )
= 4 - 2x - 2x + x^2
= x^2 - 4x + 4
b. ( x + 1 )^2 = ( 2 - x )^2
x^2 + 2x + 1 = x^2 - 4x + 4
x^2 - x^2 + 2x + 4x + 1 = 4
6x + 1 = 4
6x = 3
x = 6/3 = 1/2
