\(A=x^3+3xy+y^3\)

       \(=\left(x+y\right)\left(x^2-xy+y^2\right)+3xy\)

       \(=1.\left(x^2-xy+y^2\right)+3xy\)

       \(=x^2-xy+y^2+3xy\)

       \(=x^2+2xy+y^2\)

       \(=\left(x+y\right)^2\)

       \(=1\)

1. My father reads books every day. -> Books are read by my father every day. 

2.I buy this pencil case.-> This pencil case is bought 

3.Do you feed the dog? -> Is the dog is fed by you?

4.Tommy eats sandwiches.-> Sandwiches are eaten by Tommy

5.He does his exercises every afternoon. -> His exercises are done 

6. Sam cleans the floor twice a day. -> The floor is cleaned by Sam twice a day

7.We eat a chocolate cake. -> A chocolate cake is eaten

8.They sell this house. -> This house is sold 

1. They asked Mai how long she had lived in Hanoi.

2. Tam asked us when our mother would arrive.

3. Mr Tom asked us to do those exercises ourselves.

4. He asked me why I didn't go to the party the night before.

5. They asked us how often we had come back our village.

2,

\(a,\left(3x+2\right)^3-\left(2x-5\right)^3\)

\(=27x^3+54x^2+36x+8-8x^3+60x^2-150x+125\)

\(=19x^3+114x^2+-114x+133\)

\(b,\left(2x+7\right)^3+\left(5x-6\right)^3\)

\(=8x^3+84x^2+294x+343+125x^3-450x^2+540x-216\)

\(=133x^3-366x^2+834x+127\)

\(c,\left(3x-9\right)^2+\left(x-7\right)^3-\left(3x-1\right)^2\)

\(=9x^2-54x+81+x^3-21x^2+147x-343-9x^2+6x-1\)

\(=x^3-21x^2+99x-263\)

\(d,\left(2x-9\right)\left(2x+9\right)-\left(4x+1\right)^2+\left(5x-4\right)^3\)

\(=4x^2-81-16x^2-8x-1+125x^3-300x^2+240x-64\)

\(=125x^3-312x^2+232x-146\)

\(c,\left(x+5\right)^3-\left(x-3\right)^3-24x\left(x+2\right)\)

\(=x^3+15x^2+75x+125-x^3+9x^2-27x+27-24x^2-48x\)

\(=152\)

\(d,\left(2x-5\right)^3+\left(1-2x\right)^3+3\left(4x-5\right)^2-4\left(6x+7\right)\)

\(=8x^3-60x^2+150x-125+1-6x+12x^2-8x^3+3\left(16x^2-40x+25\right)-24x-28\)

\(=8x^3-60x^2+150x-125+1-6x+12x^2-8x^3+48x^2-120x+75-24x-28\)

\(=-77\)