Question

(а+2б)•(а-б-с)-(а-б)•(а+2б-с)+2б•(б+с)​

Answer 1

$(a + 2b) \times (a - b - c) - (a - b) \times (a + 2b - c) + 2b \times (b + c)$

${a}^{2} + ab - ac - 2 {b}^{2} - 2bc - (a - b)(a + 2b - c) + 2b(b + c)$

${a}^{2} + ab - ac - 2 {b}^{2} - 2bc - {a}^{2} + ac - bc - ab + 2 {b}^{2} + 2b(b + c)$

$- {a}^{2} + ac - bc - ab + 2 {b}^{2} + 2 {b}^{2} + 2bc$

${a}^{2} - {a}^{2} + ab - ab - ac + ac - 2 {b}^{2} + 2 {b}^{2} + 2 {b}^{2} - 2bc - bc + 2bc$

$ab - ab - ac + ac - 2 {b}^{2} + 2 {b}^{2} + 2 {b}^{2} - 2bc - bc + 2bc$

$- ac + ac - 2 {b}^{2} + 2 {b}^{2} + 2 {b}^{2} - 2bc - bc + 2bc$

$- 2 {b}^{2} + 2 {b}^{2} + 2 {b}^{2} - 2bc - bc + 2bc$

$2 {b}^{2} - 2bc - bc + 2bc$

$2 {b}^{2} - bc$