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\(5^{40}=\left(5^4\right)^{10}=625^{10}\)

Mà \(625^{10}>620^{10}\Rightarrow5^{40}>620^{10}\)

Vậy 5⁴⁰ > 620¹⁰ ( đpcm )

Ta có :

\(5^{40}=\left(5^4\right)^{10}=625^{10}\)

Vì \(625>620\Rightarrow625^{10}>620^{10}\)

Hay \(5^{40}>620^{10}\)

Vậy  \(5^{40}>620^{10}\)

_Chúc bạn học tốt_

5^{40 =} 5^4.10 = (5⁴)¹⁰ = 625¹⁰

vì 625 > 620 nên 625¹⁰ > 620¹⁰ hay 5⁴⁰ > 620¹⁰

(a^2 +b^2).(x^2 +y^2) > hoặc = (ax+by)^2 
dấu " = " xảy ra khi a/x = b/y 
Vì a/x =b/y => ay=bx 
(a^2 +b^2).( x^2 +y^2)= a^2.x^2 +a^2.y^2 +b^2.x^2 + b^2.y^2 
= a^2.x^2 + b^2.x^2 +b^2.x^2 +b^2.y^2 
= (ax)^2 +2.b^2.x^2 + (by)^2 
= (ax)^2 +2.ax.by + (by)^2 ( tách b^2.x^2= b.x.b.x = a.y.b.x= ax.by) 
= (ax+by)^2 
=> đpcm +5*hjhjhkj

1 My parents go shopping twice a week

2 Hoa's house has a balcony

3 My brother usually plays badminton with his friends

4 My favorite book is Tam and Cam. What is yours?

5 There are 10 pencil cases on the table

1, My parents go shopping twice a week.

2, Hoa's house has a balcony.

3, My brother usually plays badminton with his friends.

4, My favorite book is Tam and Cam. What's yours?

5, There are ten pencil cases on the table.

\(3,\\ a,\dfrac{\left(1+\sqrt{x}\right)^2-4\sqrt{x}}{1-\sqrt{x}}\\ =\dfrac{\sqrt{x}-2\sqrt{x}+1}{1-\sqrt{x}}=\dfrac{\left(1-\sqrt{x}\right)^2}{1-\sqrt{x}}=1-\sqrt{x}=1-\sqrt{2}\)

\(b,\dfrac{\left(\sqrt{x}-\sqrt{y}\right)^2+4\sqrt{xy}}{1+\sqrt{xy}}\\ =\dfrac{x+2\sqrt{xy}+y}{1+\sqrt{xy}}=\dfrac{\left(\sqrt{x}+\sqrt{y}\right)^2}{1+\sqrt{xy}}\\ =\dfrac{\left(\sqrt{2}+\sqrt{3}\right)^2}{1+\sqrt{6}}=\dfrac{5+2\sqrt{6}}{1+\sqrt{6}}\\ =\dfrac{\left(5+2\sqrt{6}\right)\left(\sqrt{6}-1\right)}{5}\\ =\dfrac{3\sqrt{6}+7}{5}\)

12x+3.2³=2³.x-4.3²

12x+3.8=8.x-4.9

12x+24=8x-36

12x-8x=36-24

4x=12

x=12:4=3

      \(12x+3\cdot2^3=2^3x-4\cdot3^2\)

\(\Rightarrow12x+24=8x-36\)

\(\Rightarrow12x-8x=-36-24\)

\(\Rightarrow4x=-60\)

\(\Rightarrow x=-15\)

Vay x=-15

k mk nhA