A

64x⁴-48x²+9

=(8x²)²-2.8.x².3+3²

=(8x²-3)²

=(8x²-3).(8x²-3)

4x²+4x+15

=(2x)²+2x2+2²-2²+15

=(2x+2)²+11

vì (2x+2)²≥0

=>(2x+2)²+11≥11

Vậy giá trị nhỏ nhất của biểu thức là 11

5/2-1/6250

=\(\dfrac{15625}{6250}\)-\(\dfrac{1}{6250}\)

=\(\dfrac{15624}{6250}\)

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A : Hello, I want to go to Hawaii for vacation next week and I need to book a flight .

B : Okay, sir, I can help you with that. When would you like to arrive in Hawaii?

A :On the 17th. I'm planning to stay for a week, so I'd like to leave on the 24th.

B : I have ticket for $1,200. Is that okay?

A : Yes, that's fine

B : Great. I will send you an e-mail to confirm the ticket

1.you Shouldn't park

2.what should I cook

3.You should

4.You shouldn't

5.We should

6.Should I send 

7.I should  apply

8.I should  write

9.I shouldn't

10.we should complain

11.should I buy

D