I don't know how to show you the steps but I'll hope u'll understand...
a. -x^2y+4xy^3-(xy^3-9x^2y)
-x^2y+4xy^3-xy^3-9x^2y. combine like terms
Answer: 8x^2y+3xy^3
b. ab(b^2-4ac) distribute
Answer: ab^3-5a^2bc
c.(4-7x)^2. expand and the expression (a-b)^2 = a^2-2ab+b^2
16-59x+49x^2. comunitib property... 're order the terms
Answer: 49x^2-56x+16
d. (5a^5b^3)^2. use exponent rule
5^2×(a^5)^2×(b^3)^2
Answer: 25a^10b^6
I hope I hepled...
