Question

помогите а то я тупой

Answer 1

$\Large \sf \ \: \boxed{ \Huge{a).}} \: \frac{3}{4} x {y}^{2} \times 16y = 3 \times 4x {y}^{2 + 1} = \boxed{ \huge12x {y}^{3} }; \\ \boxed{ { \Huge b).}} \: \Large \sf \: 1.6 {a}^{2} c \times \bigg( - 2a {c}^{2} \bigg) = - 3.2 {a}^{2 + 1} {c}^{1 + 2} = \boxed{\huge \: - 3.2 {a}^{3} {c}^{3} }; \\ \boxed{\Huge \: v).} \sf \Large \: - {x}^{3} {y}^{4} \times 1.4 {x}^{6} {y}^{5} = - 1.4 {x}^{6 + 3} {y}^{5 + 4} = \boxed{ \huge \: - 1.4 {x}^{9} {y}^{9} }.$