Bonsoir,
1.a. AD = x + 3 + x - 2 = 2x + 1
b. A = (2x + 1)² = 4x² + 4x + 1
c. B = (x + 3) (2x + 1)
d. C = (x - 2) (2x + 1)
2.a. B = (x + 3) (2x + 1) = 2x² + x + 6x + 3 = 2x² + 7x + 3
C = (x - 2) (2x + 1) = 2x² + x - 4x - 2 = 2x² - 3x - 2
B+C = (x + 3) (2x + 1) + (x - 2) (2x + 1) = (2x + 1) (x + 3 + x - 2) = (2x + 1) (2x + 1)
B+C = (2x + 1)² = 4x² + 4x + 1
b. B+C = 4x² + 4x + 1 = A