Question

find the product (5-2x)(3+2x)by suitable identity

Answer 1

5(3+2x)-2x(3+2x)
= 15 + 10x - 6x - 4x²
= 15 + 4x - 4x²
= -4x² + 4x + 15

Answer 2

$(5 - 2x)(3 + 2x) \\ 15 + 10x - 6x - 4{x}^{2} \\ 15 + 4x - 4 {x}^{2} \\ - 4 {x}^{2} + 4x + 15 \\ - (4{x}^{2} - 4x - 15) \\ 4 {x}^{2} - 4x - 15 \\ 4 {x}^{2} - (10 - 6)x - 15 \\ 4 {x}^{2} - 10x + 6x - 15 \\ 2x(2x - 5) + 3(2x - 5) \\ (2x + 3)(2x - 5) \\ or \\ 2x + 3 = 0 \\ 2x = - 3 \\ x = \frac{ - 3}{2} \\ else \: \\ 2x - 5 = 0 \\ 2x = 5 \\ x = \frac{5}{2}$