[toán 10] đại số

N

nguyenbahiep1

$a^3 + a+1+1 \geq 4a \\ \\ b^3 + b+1+1 \geq 4b \\ \\ \Rightarrow a^3+b^3 + a+b+ 4 \geq 4(a+b) \\ \\ a^3+b^3 \geq 8 - 2 - 4 = 2 \\ \\ a = b = 1$
 
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