1. Упростите выражения: a) $$3a^2b \cdot b^4a^4 =$$ b) $$\left(\frac{3}{7}a^2b\right)^2 \cdot \frac{7}{3}b^2a =$$ в) $$-5y(y+3)+(y-4)^2 =$$

a) $$3a^2b \cdot b^4a^4 = 3a^{2+4}b^{1+4} = 3a^6b^5$$ б) $$\left(\frac{3}{7}a^2b\right)^2 \cdot \frac{7}{3}b^2a = \frac{9}{49}a^4b^2 \cdot \frac{7}{3}b^2a = \frac{9 \cdot 7}{49 \cdot 3} a^{4+1}b^{2+2} = \frac{3}{7}a^5b^4$$ в) $$-5y(y+3)+(y-4)^2 = -5y^2-15y + (y^2 - 8y + 16) = -5y^2 - 15y + y^2 - 8y + 16 = -4y^2 - 23y + 16$$