\(\forall\) là với mọi nha bn.

HSG

Mark the letter A, B, C or D on your answer sheet to indicate the sentence which has the same meaning as the original one.
He wants his wife to quit her job and look after their children.

A. He would like his wife to stop working and looking after their children.

B. He wants to quit his job and his wife look after their children.

C. He would like his wife to continue working in spite of looking after their children.

D. He would like his wife to stop working and look after their children.

a) (5x²y-5xy²+xy) + (xy-x²y²+5xy²)

= 5x²y-5xy²+xy+xy-x²y²+5xy²

= 5x²y+(5xy²-5xy²)+(xy+xy)-x²y²

= 5x²y+2xy-x²y²

b) (x²+y²+z²) + (x²-y²+z²)

= x²+y²+z²+x²-y²+z²

= (x²+x²)+(y²-y²)+(z²+z²)

= 2x²+2z²

A(x) = 2x - 7 + (x - 14)

Để đa thức A(x) có nghiệm thì A(x) = 0

hay 2x - 7 + (x - 14) = 0

\(\Leftrightarrow\) 2x - 7 + x - 14 = 0

\(\Leftrightarrow\) 3x - 21 = 0

\(\Leftrightarrow\) 3x = 21

\(\Leftrightarrow\) x = 7

Vậy x = 7 là nghiệm của đa thức A(x)