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x(y - z) + 2(z - y)
= x(y - z) - 2(y - z)
= (x - 2)(y - z)
(2x - 3y)(x - 2) - (x + 3)(3y - 2x)
= (2x - 3y)(x - 2) + (x + 2)(2x - 3y)
= (2x - 3y)(x - 2 + x + 2)
= 2x(2x - 3y)
\(=\left(3x+15\right)^2-\left(x-7\right)^2\\ =\left(3x+15-x+7\right)\left(3x+15+x-7\right)\\ =\left(2x+22\right)\left(4x+8\right)\\ =2\left(x+11\right)4\left(x+2\right)\\ =8\left(x+11\right)\left(x+2\right)\)
\(=\left(x^2+y^2-5\right)^2-\left[2\left(xy+2\right)\right]^2\\ =\left(x^2+y^2-5-2xy-4\right)\left(x^2+y^2-5+2xy+4\right)\\ =\left[\left(x-y\right)^2-9\right]\left[\left(x+y\right)^2-1\right]\\ =\left(x-y-3\right)\left(x-y+3\right)\left(x+y-1\right)\left(x+y+1\right)\)
\(=\left(x^2+y^2-5\right)^2-4\left(xy+2\right)^2\)
\(=\left(x^2+y^2-5\right)^2-\left(2xy+4\right)^2\)
\(=\left(x^2+y^2-5-2xy-4\right)\left(x^2+y^2-5+2xy+4\right)\)
\(=\left[\left(x-y\right)^2-9\right]\left[\left(x-y\right)^2-1\right]\)
\(=\left(x-y-3\right)\left(x-y+3\right)\left(x-y-1\right)\left(x-y+1\right)\)
a) x.(1-x)+(x-1)2
=x.1-x2+x2-2.x2.1+12
=x-x2+x2-2.x2+1
=(-x2+x2-2x2)+1
=-2x2+1
b)(x+1)2-3.(x+1)
=x2+2.x2.1+12-3.x+3
=x2+2.x2+1-3x+3
=(x2+2x2)+(1+3)-3x
=3x2-3x+4
c)3x.(x-1)2-(1-x)3
=3x.x2-2,x2.1+12-13-3.12.x+3.x.12=3x.x2-2x2+1-1-3x+3x=(3x-3x+3x)(x2-2x2)(1-1)=3x.(-x2)
\(2x+2y-x^2-xy\)
\(=2\left(x+y\right)-x\left(x+y\right)\)
\(=\left(x+y\right)\left(2-x\right)\)
uses crt;
var a:array[1..200]of integer;
i,t:integer;
begin
clrscr;
for i:=1 to 200 do
begin
write('A[',i,']='); readln(a[i]);
end;
writeln('Cac phan tu le nho hon 200 la: ');
for i:=1 to n do
if (a[i] mod 2<>0) and (a[i]<200) then write(a[i]:4);
writeln;
t:=0;
for i:=1 to n do
if (50<a[i]) and (a[i]<80) then t:=t+sqr(a[i]);
writeln('Tong binh phuong cac phan tu thuoc khoang (50;80) la: ',t);
readln;
end.
\(x\left(x+y\right)-5\left(x+y\right)=\left(x+y\right)\left(x-5\right)\)
Câu này dễ mà
a) x2(1-2y+xy)
b)3x(x+27-4y2)