a: ĐKXĐ: \(x\notin\left\{3;-3\right\}\)

\(M=\left(\dfrac{x+3}{x-3}-\dfrac{18}{\left(x-3\right)\left(x+3\right)}+\dfrac{x-3}{x+3}\right):\dfrac{x+3-x-1}{x+3}\)

\(=\dfrac{x^2+6x+9-18+x^2-6x+9}{\left(x-3\right)\left(x+3\right)}\cdot\dfrac{x+3}{2}\)

\(=\dfrac{2x^2}{x-3}\cdot\dfrac{1}{2}=\dfrac{x^2}{x-3}\)

b: Để M nguyên thì \(x^2-9+9⋮x-3\)

\(\Leftrightarrow x-3\in\left\{1;-1;3;-3;9;-9\right\}\)

hay \(x\in\left\{4;2;6;0;12;-6\right\}\)

Muốn tình % của a và b ta có :

              A : B x 100% nha bn !

Vậy áp dụng bài này ta có :

             Tỉ số % của 0.3 và 0.96 là : 0.3 : 0.96 x 100 =31.25%

 Chúc bn học tốt nhé ! 

nbxjasc

1. There are ten dogs in the kennel

2. My grandma is the oldest in my family

3. Thuy is heavier than Tung

4. I enjoy eating sandwich

5. I can't eat the soup now because it ís hot

1. were ten dogs

2. the oldest person in my family

3. not as thin as Tung

4. eating sandwich so much

5. Because the soup is hot, I can't eat it now

1. There are ten dogs in the kennel.

2. My grandma is the oldest in my family.

3. Thuy is heavier than Tung.

4. I enjoy eating sandwich.

5. I can't eat the soup now because it is hot.
7.hừm.............ờ...........ờ..........( mk không biết nữa)

b: \(=\dfrac{9}{2}\left(\dfrac{2}{2\cdot4}+\dfrac{2}{4\cdot6}+...+\dfrac{2}{98\cdot100}\right)\)

\(=\dfrac{9}{2}\left(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+...+\dfrac{1}{98}-\dfrac{1}{100}\right)\)

\(=\dfrac{9}{2}\cdot\dfrac{49}{100}=\dfrac{441}{200}\)

b, Thay x=1 vào g(x) ta có:

\(g\left(1\right)=100.1^{100}+99.1^{99}+...+2.1^2+1+1\\ =100.1+99.1+...+2.1+1+1\\ =100+99+...+2+1+1\\ =\left(100+1\right).100:2+1\\ =5051\)

c, Thay x=-1 vào h(x) ta có:

\(h\left(-1\right)=1-\left(-1\right)+\left(-1\right)^2-\left(-1\right)^3+...+\left(-1\right)^{100}\\ =1+1+1+...+1\\ =101\)

b: BCNN(21;55)=1155

\(B=\sqrt{14+2\sqrt{10}+2\sqrt{14}+2\sqrt{35}}\)

\(=\sqrt{2}+\sqrt{5}+\sqrt{7}\)

a: Xét ΔAHB vuông tại H và ΔAKC vuông tại K có

AB=AC

góc BAH chung

=>ΔAHB=ΔAKC

=>AH=AK

b: Xét ΔAKI vuông tại K và ΔAHI vuông tại H có

AI chung

AH=AK

=>ΔAKI=ΔAHI

=>KI=HI

AK=AH

IK=IH

=>AI là trung trực của HK