Question

tim gia tri nho nhat cua bieu thuc \(A=\left|1-2x\right|-2009\)

tim 2 so x,y biet \(\frac{x}{y}=\frac{2}{5}\)va x+y=-21

so sanh \(2^{225}vs3^{150}\)

Answer 1

1)

vì | 1 - 2x | \(\ge\)0 \(\Rightarrow\)| 1 - 2x | - 2009 \(\ge\)-2009

\(\Rightarrow\)GTNN của A là -2009 khi | 1 - 2x | = 0 hay x = \(\frac{1}{2}\)

2)

\(\frac{x}{y}=\frac{2}{5}\Rightarrow\frac{x}{2}=\frac{y}{5}=\frac{x+y}{2+5}=\frac{-21}{7}=-3\)

\(\Rightarrow x=\left(-3\right).2=-6;y=\left(-3\right).5=-15\)

3) 

2²²⁵ = ( 2³ )⁷⁵ = 8⁷⁵

3¹⁵⁰ = ( 3² )⁷⁵ = 9⁷⁵

vì 8⁷⁵ < 9⁷⁵ nên 2²²⁵ < 3¹⁵⁰