bonjour

2(x+7)(3-2x)+(5x-2) (4x+1)

= ( 2 x + 14 ) ( 3 - 2 x ) + 20 x² + 5 x - 8 x - 2

= 6 x - 4 x² + 42 - 28 x + 20 x² - 3 x - 2

=  16 x² - 25 x + 40

2(x+7)(3-2x)+(5x-2) (4x+1) = (2*x+2*7) (3-2x) + (5x-2) (4x+1)

= (2x+14) (3-2x) + ((5x-2) (4x+1)

puisque tu sais que (a+b) (c+d) = a*c+a*d+b*c+b*d, on aura :

= 6x - 4x² + 42 - 28x + 20x² + 5x - 8x - 2

= -4x² + 20x²  -22x  - 3x + 42 - 2

= 16x² - 25x + 40