Répondre :
1) \( A = 3(x+2) \)
\( = 3x + 6 \)
\( B = -3(4a-5) \)
\( = -12a + 15 \)
2) \( C = 5(x-3) +10x² \)
\( = 5x - 15 + 10x² \)
\( = 10x² + 5x - 15 \)
\( D = x(2-4x) +6x²+7x -8 \)
\( = 2x - 4x² + 6x² + 7x - 8 \)
\( = 2x + 2x² + 7x - 8 \)
\( = 2x² + 9x - 8 \)
3) \( E = (3x+1)(5x+3) \)
\( = 15x² + 9x + 5x + 3 \)
\( = 15x² + 14x + 3 \)
\( F = (8-7x)(10+9x) \)
\( = 80 - 70x + 72x - 63x² \)
\( = 80 + 2x - 63x² \)
4) \( G = (2x+3)² \)
\( = (2x+3)(2x+3) \)
\( = 4x² + 6x + 6x + 9 \)
\( = 4x² + 12x + 9 \)
\( H = (3y -4)² \)
\( = (3y -4)(3y -4) \)
\( = 9y² - 12y - 12y + 16 \)
\( = 9y² - 24y + 16 \)
5) \( I = (-6x -3)(5 -3x) +4(7x -6) \)
\( = 30 - 18x - 15x + 9x² + 28x - 24 \)
\( = 9x² - 5x + 6 \)