Áp dụng định lí Pytago:

`NP^2=MN^2+MP^2`

`<=> MP=\sqrt(13^2-5^2)=12(cm)`

Các tỉ số lượng giác `\hatN` là:

`sinN=(MP)/(NP)=12/13`

`cosN=(MN)/(NP)=5/13`

`tanN=(MP)/(MN)=12/5`

`cotN=(MN)/(MP)=5/12`

`(n^2+3n+1)^2-1`

`=(n^2+3n+1)-1^2`

`=(n^2+3n+1+1)(n^2+3n+1-1)`

`=(n^2+3n+2)(n^2+3n)`

`=(n+1)(n+2)n(n+3)`

`=n(n+1)(n+2)(n+3)` là tích của 4 số tự nhiên liên tiếp.

`=> n(n+1)(n+2)(n+3) vdots 24`

live -> lives

on -> in

is -> has

in seven -> at seven

in -> at

his student -> her student

on -> from

teach -> teaches

On the evening -> In the evening

listens book -> reads book

always go -> always goes

`|x(x-3)|=2/3 x`

TH1: `x(x-3)>=0`

`x(x-3)=2/3 x`

`x^2 -3x = 2/3 x`

` x^2- 11/3 x=0`

`x(x-11/3)=0`

`[(x=0),(x=11/3):}`

TH2: `x(x-3)<0`

`-x(x-3)=2/3 x`

`-x^2+3x=2/3x`

`-x^2+7/3 x=0`

`x(-x+7/3)=0`

`[(x=0(L)),(x=7/3):}`

Vây `x=0; x=11/3 ; x=7/3`

`8/5 .2/3 + (-5.5)/(3.5) = 16/15 - 5/3 = -3/5`

b) 6/7+5/8 :5 -3/16 .(-2)^2=6/7 + 1/8 - 3/16 .4`

`=55/56 - 3/4`

`=13/56`

It was such a hard cake that I couldn't eat it.

If it hadn't rained, we would have gone.

My mother can cook better than I.

Các đơn thức đồng dạng: `xy^2 ; 2xy^2 ; 3/4 xy^2 ; -5xy^2; ....`

Áp dụng công thức Heron:

`p=(a+b+c)/2=(10+10+10)/2=15`

`=> S=\sqrt(p(p-a)(p-b)(p-c)) = \sqrt(15(15-10)^3) = 25\sqrt3`

- Thank you for your inspiring compliments. <33