Giúp mik với. Bài này mik phải hoàn thành trong hôm nay![]()

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\(\frac{7}{x}=\frac{y}{27}=-\frac{42}{54}\)
\(\Leftrightarrow\frac{7}{x}=\frac{y}{27}=-\frac{7}{9}\)
Có \(\frac{7}{x}=-\frac{7}{9}\)
\(\Leftrightarrow x=-9\)
Lại có \(\frac{y}{27}=-\frac{7}{9}\)
\(\Leftrightarrow x=-21\)
uses crt;
var st:string;
d,i,t,x,y,a,b:integer;
begin
clrscr;
readln(st);
d:=length(st);
for i:=1 to d do write(st[i]:4);
writeln;
t:=0;
for i:=1 to d do
begin
val(st[i],x,y);
t:=t+x;
end;
writeln(t);
val(st[d],a,b);
if (a mod 2=0) then write(1)
else write(-1);
readln;
end.
#include <bits/stdc++.h>
using namespace std;
long long a[1000],i,n,t,dem,t1;
int main()
{
cin>>n;
for (i=1; i<=n; i++) cin>>a[i];
t=0;
for (i=1; i<=n; i++) if (a[i]%2==0) t+=a[i];
cout<<t<<endl;
t1=0;
dem1=0;
for (i=1; i<=n; i++)
if (a[i]<0)
{
cout<<a[i]<<" ";
t1+=a[i];
dem1++;
}
cout<<endl;
cout<<fixed<<setprecision(1)<<(t1*1.0)/(dem1*1.0);
return 0;
}
#include <bits/stdc++.h>
using namespace std;
long long a,b;
//chuongtrinhcon
long long gcd(long long a,long long b)
{
if (b==0) return(a);
return gcd(b,a%b);
}
//chuongtrinhchinh
int main()
{
cin>>a>>b;
cout<<max(a,b)<<endl;
cout<<gcd(a,b)<<endl;
if ((a>0 && b>0) or (a<0 && b<0)) cout<<a/gcd(a,b)<<" "<<b/gcd(a,b);
else cout<<"-"<<-a/gcd(-a,b)<<" "<<b/gcd(-a,b);
return 0;
}
a) Có : AB ⊥ AC tại A ( gt )
CD ⊥ AC tại C ( gt )
=> AB//CD ( Quan hệ từ vuông góc đến song song )
b) Kéo dài CD ( như hình vẽ ).

Có : Góc ACB + Góc C1 = 180o ( Tính chất 2 góc kề bù )
90o + Góc C1 = 180o ( Thay số )
Góc C1 = 90o
Có : Góc C1 + Góc C2 = Góc ACE ( Tính chất cộng góc )
90o + Góc C2 = 140o ( Thay số )
90o + Góc C2 = 50o
Có : Góc C2 + Góc CEF = 50o + 130o = 180o
Mà 2 góc này nằm ở vị trí phía trong cùng.
=> CD//EF ( dhnb )
My taste in art is not the same as my sister's
I think romantic films aren't as interesting as action films
I don't speak Japanese and my new friend doesn't, either
Nester goes climbing less than before
He's had a cold for 2 days because he didn't wear enough clothes
I will spend an hour gettign this task done
My father prefers tea to coffee
Eat less or you will be obese








B2: a) \(\left(x+\dfrac{1}{2}\right)\left(\dfrac{1}{2}-x\right)\)
\(=-\left(x+\dfrac{1}{2}\right)\left(x-\dfrac{1}{2}\right)\)
\(=-x^2+\dfrac{1}{4}\)
b) \(\left(3x-2y\right)\left(3x+2y\right)\)
\(=\left(3x\right)^2-\left(2y\right)^2\)
\(=9x^2-4y^2\)
c) \(\left(x-3\right)\left(3+x\right)\)
\(=x^2-3^2\)
\(=x^2-9\)
d) \(x^2+6x+9\)
\(=x^2+2\cdot3\cdot x+3^2\)
\(=\left(x+3\right)^2\)
e) \(9x^2-6x+1\)
\(=\left(3x\right)^2-2\cdot3x\cdot1+1^2\)
\(=\left(3x-1\right)^2\)
f) \(x^2y^2+xy+\dfrac{1}{4}\)
\(=\left(xy\right)^2+2\cdot\dfrac{1}{2}\cdot xy+\left(\dfrac{1}{2}\right)^2\)
\(=\left(xy+\dfrac{1}{2}\right)^2\)
g) \(\left(x-y\right)^2+6\left(x-y\right)+9\)
\(=\left(x-y\right)^2+2\cdot3\cdot\left(x-y\right)+3^2\)
\(=\left(x-y+3\right)^2\)
h) \(x^2+8x+16\)
\(=x^2+2\cdot4\cdot x+4^2\)
\(=\left(x+4\right)^2\)
i) \(9x^2-24x+16\)
\(=\left(3x\right)^2-2\cdot3x\cdot4+4^2\)
\(=\left(3x-4\right)^2\)
k) \(x^2-3x+\dfrac{9}{4}\)
\(=x^2-2\cdot\dfrac{3}{2}\cdot x+\left(\dfrac{3}{2}\right)^2\)
\(=\left(x-\dfrac{3}{2}\right)^2\)
l) \(4x^2y^4-4xy^3+y^2\)
\(=\left(2xy^2\right)^2-2\cdot2xy^2\cdot y+y^2\)
\(=\left(2xy^2-y\right)^2\)
m) \(9x^2-6x+1\)
\(=\left(3x\right)^2-2\cdot3x\cdot1+1\)
\(=\left(3x-1\right)^2\)
Thank you very much Phong