Question

a)(5a-7)(3a+1)=

б)(3b+7)(4-3b)=

Answer 1

а)(5a-7)(3a+1) = 15a^2-16a-7

б)(3b+7)(4-3b) = -9b^2-9b+28

Answer 2

$\bf \: a).(5a-7)(3a+1)=15 {a}^{2} + 5a - 21a - 7 = \huge \: 15 {a}^{2} - 16a - 7; \\ \bf \: </p><p>b).(3b+7)(4-3b)=12b - 9 {b}^{2} + 28 - 21b = \huge \: - 9 {b}^{2} - 9b + 28.$