If x + y = 7 and xy = 10, find:
(x³ + y³)² - 9x²y²(x + y)²

Question

Accepted Answer

1. Use the identity $x^3+y^3=(x+y)^3-3xy(x+y)$. With $x+y=7$ and $xy=10$ we get $x^3+y^3=7^3-3*10*7=343-210=133$.
2. Square it: $(x^3+y^3)^2=133^2=17689$.
3. Compute the other term: $9x^2y^2(x+y)^2=9*(10^2)*(7^2)=9*100*49=44100$.
4. Subtract: $17689-44100=-26411$. So the value is **-26411**, which is choice (b).

FINAL_ANSWER: b

Answer

Answer

Answer