Lời giải:
a.

Nếu $m=3$ thì pt trở thành:
$x^2+4x-5=0$

$\Leftrightarrow (x-1)(x+5)=0$

$\Leftrightarrow x=1$ hoặc $x=-5$

b.

Để pt có 2 nghiệm pb $x_1,x_2$ thì:

$\Delta'=4+m^2-4>0\Leftrightarrow m^2>0\Leftrightarrow m\neq 0$

PT có 2 nghiệm $(-2+m, -2-m)$

Khi đó:

\(x_2=x_1^3+4x_2^2\Leftrightarrow \left[\begin{matrix} -2+m=(-2-m)^3+4(-2+m)^2\\ -2-m=(-2+m)^3+4(-2-m)^2\end{matrix}\right.\)

\(\Leftrightarrow \left[\begin{matrix} -m^3+2m^2-29m+10=0\\ m^3-2m^2+29m+10=0\end{matrix}\right.\)

Nghiệm khá xấu, cảm giác đề cứ sai sai bạn ạ.

37 have just been finished

38 seen my sister for 3 weeks

39 snow, all flights wouldn't be cancelled

40 I can't swim, I don't go scuba diving with Terry

#include <bits/stdc++.h>

using namespace std;

double a,b,c,p,s;

int main()

{

cin>>a>>b>>c;

p=(a+b+c)/2;

s=sqrt(p*(p-a)*(p-b)*(p-c));

cout<<fixed<<setprecision(2)<<p;

return 0;

}

1: 

uses crt;

var a,b,c,max,min:longint;

begin

clrscr;

readln(a,b,c);

max=a;

if max<b then max:=b;

if max<c then max:=c;

min:=a;

if min>c then min:=c;

if min>b then min:=b;

writeln(max,' ',min);

readln;

end.

1.2 với \(x\ge0,x\in Z\)

A=\(\dfrac{2\sqrt{x}+7}{\sqrt{x}+2}=2+\dfrac{3}{\sqrt{x}+2}\in Z< =>\sqrt{x}+2\inƯ\left(3\right)=\left(\pm1;\pm3\right)\)

*\(\sqrt{x}+2=1=>\sqrt{x}=-1\)(vô lí)

*\(\sqrt{x}+2=-1=>\sqrt{x}=-3\)(vô lí
*\(\sqrt{x}+2=3=>x=1\)(TM)

*\(\sqrt{x}+2=-3=\sqrt{x}=-5\)(vô lí)

vậy x=1 thì A\(\in Z\)