9 x 2 = 18

9 x 5 = 45

9 x 8 = 72

9 x 10 = 90

2 x 9 = 18

5 x 9 = 45

8 x 9 = 72

10 x 9 = 90

a: \(2^{2x-2}>=8\)

=>\(2^{2x-2}>=2^3\)

=>2x-2>=3

=>2x>=5

=>\(x>=\dfrac{5}{2}\)

b: \(4^{2x+2}< =16\)

=>\(4^{2x+2}< =4^2\)

=>2x+2<=2

=>2x<=0

=>x<=0

c: \(5^{x-9}>5^2\)

=>x-9>2

=>x>11

d: \(9^{x+2}< 9\)

=>\(9^{x+2}< 9^1\)

=>x+2<1

=>x<-1

e: \(9^{x-1}>9^{x^2-x-9}\)

=>\(x-1>x^2-x-9\)

=>\(x^2-x-9-x+1< 0\)

=>\(x^2-2x-8< 0\)

=>(x-4)(x+2)<0

=>-2<x<4

C

Đẳng thức nào đúng:

 A.(x-3)^2=x^2+6x+9                              B.(x-3)^2=9-x^2

C.(x-3)^2=9-6x+x^2                               D.(x-3)^2=x^2-3x+9

Câu C

a: \(\frac{x+3+2\cdot\sqrt{x^2-9}}{2x-6+\sqrt{x^2-9}}\)

\(=\frac{\sqrt{\left(x+3\right)^2}+2\cdot\sqrt{x+3}\cdot\sqrt{x-3}}{2\cdot\sqrt{\left(x-3\right)^2}+\sqrt{\left(x-3\right)}\cdot\sqrt{x+3}}\)

\(=\frac{\sqrt{x+3}\left(\sqrt{x+3}+2\sqrt{x-3}\right)}{\sqrt{x-3}\left(2\sqrt{x-3}+\sqrt{x+3}\right)}=\frac{\sqrt{x+3}}{\sqrt{x-3}}=\frac{\sqrt{x^2-9}}{x-3}\)

b: \(T=\frac{x^2+5x+6+x\cdot\sqrt{9-x^2}}{3x-x^2+\left(x+2\right)\cdot\sqrt{9-x^2}}\)

\(=\frac{\left(x+2\right)\left(x+3\right)+x\cdot\sqrt{\left(3-x\right)\left(3+x\right)}}{x\left(3-x\right)+\left(x+2\right)\cdot\sqrt{\left(3-x\right)\left(3+x\right)}}\)

\(=\frac{\sqrt{x+3}\left\lbrack\left(x+2\right)\cdot\sqrt{x+3}+x\cdot\sqrt{3-x}\right\rbrack}{\sqrt{3-x}\left\lbrack x\cdot\sqrt{3-x}+\left(x+2\right)\cdot\sqrt{x+3}\right\rbrack}=\frac{\sqrt{3+x}}{\sqrt{3-x}}\)

a) 9 x 2 + 4 = 18 + 47 = 65

b) 9 x 4 x 2 = 36 x 2 = 72

c) 9 x 9 – 18 = 81 – 18 = 63

d) 9 x 6 : 3 = 54 : 3 = 18

\(\frac{\left(x-9\right)^3}{2\left(9-x\right)}\)

\(=\frac{-\left(9-x\right)^3}{2\left(9-x\right)}=\frac{-\left(9-x\right)^2}{2}\)

\(=-\frac{\left(x-9\right)^2}{2}\)

Cái này mới đúng nè bạn

4,468397968658136e+22

4,468397968658136e+22

Trả lời
3 
Đánh dấu
điền các dấu thích hợp :+,-,x,:
9...9...9...9 =9
(/hoi-dap/detail/214795928246.html)
9 x (9 - 9) + 9 =0