Mng giúp em với
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Bài 2:
a: \(f\left(x\right)=-9x^3-2x^2+6x-3\)
\(G\left(x\right)=9x^3-6x+53\)
b: \(H\left(x\right)=9x^3-6x+53-9x^3-2x^2+6x-3=-2x^2+50\)
c: Đặt H(x)=0
=>2x2-50=0
=>x=5 hoặc x=-5
Câu 2:
uses crt;
var a:array[1..100]of integer;
i,n,t:integer;
begin
clrscr;
write('Nhap n='); readln(n);
for i:=1 to n do
begin
write('A[',i,']='); readln(a[i]);
end;
t:=0;
for i:=1 to n do
if (4<a[i]) and (a[i]<15) then t:=t+a[i];
writeln(t);
readln;
end.
\(c,A\left(-2;2\right)\inđths\Leftrightarrow-2a+b=2\left(1\right)\\ Đths//Ox\Leftrightarrow a=0;b=y\left(2\right)\\ \left(1\right)\left(2\right)\Leftrightarrow a=0;b=2\)
1.
\(1+tan\alpha+tan^2\alpha+tan^3\alpha\)
\(=1+\dfrac{sin\alpha}{cos\alpha}+\dfrac{sin^2\alpha}{cos^2\alpha}+\dfrac{sin^3\alpha}{cos^3\alpha}\)
\(=1+\dfrac{sin\alpha}{cos\alpha}+\dfrac{sin^2\alpha}{cos^2\alpha}\left(1+\dfrac{sin\alpha}{cos\alpha}\right)\)
\(=\left(\dfrac{sin^2\alpha}{cos^2\alpha}+1\right)\left(1+\dfrac{sin\alpha}{cos\alpha}\right)\)
\(=\dfrac{1}{cos^2\alpha}\left(1+\dfrac{sin\alpha}{cos\alpha}\right)=\dfrac{sin\alpha+cos\alpha}{cos^3\alpha}\)
2.
\(\dfrac{1+tan^4x}{tan^2x+cot^2x}\)
\(=tan^2x.\dfrac{1+tan^4x}{tan^4x+cot^2x.tan^2x}\)
\(=tan^2x.\dfrac{1+tan^4x}{1+tan^4x}\)
\(=tan^2x\)