Ta có:(x+2)2-(x+4)(x-4)=x2+4x+4-x2+16=4x+20=4(x+5)
\(\left(x+2\right)^2-\left(x+4\right)\left(x-4\right)\)
\(=x^2+4x+4-x^2+16=4x+20\)
Câu 14. Tích ( 2).( 2) x x bằng:
A. 2 x 4 .
B. 2 x 4 .
C. 2 x x 4 4 .
D. 2 x x 4 4
(\(\dfrac{3x-2}{x-2}\) - \(\dfrac{x}{x+2}\)+ \(\dfrac{4}{x^2-4}\)) : \(\dfrac{x+3}{x^2-4}\)
Rút gọn các biểu thức sau
a. (x-2 ) .(x^2 +2x + 4 ) - (x^3 +2)
b. (x+4) . (x^2 -4x + 16 ) - (x-4) . (x^2 + 4x +16)
c. (x-2 )^3 - x (x+1). (x+1). (x+1) +6x( x-3)
d,(x-2).(x^2-2x+4 ) .(x+2) .(x^2 +4x +4 )
P=(x^2-1/x^4-x^2+1 + 2/x^6+1 - 1/x^2+1).(x^2 - x^4+x^2-1/x^4+x^2+1 )
a,Rút gọn b,Tìm GTLN
Tính:
1, (x-1)(x^2+x+1)
2, (x-2)(x^2+2x+4)
3, (x+4)(x^2-4x+16)
4, (3x+2)(9x^2-6x+4)
\(P=\left(\dfrac{x^2-1}{x^4-x^2+1}+\dfrac{2}{x^6+1}-\dfrac{1}{x^2+1}\right).\left(x^2-\dfrac{x^4+x^2-1}{x^4+x^2+1}\right)\)
a,Rút gọn b,Tìm GTLN
Bài 1:Tìm x
1,x.(1-6.x)-6.x.(4-x)=46
2,(3.x-2).(3.x+2)-9.(x-2)2=20
3,x.(x3+3.x-4)-(x4+3x2)=20
4,x.(2.x-3)+2.x.(1-x)=9
5,x.(12.x-3)-12.x.(x-2)=54
Bài 1: Áp dụng những hằng đẳng thức để tìm x
a) -(x+3)(x-4)+(x+1)(x-1)=10
b) (2x-1)(x-2)-(x+3)(2x-7)=3
c) (x-5)(4-x)-(x-1)(x+3)=-2x
d) 3(x+7)(x-7)-(x-1)(3x+2)=13
e) 5(x-3)(x-7)-(5x+1)(x-2)=8
f) (3x-4)(x-2)=3x(x-9)-10
g) 5x(x-3)=(x-2)(5x-1)-5
h) 6(x-3)(x-4)-6x(x-2)=4
i) (x-2)(x+3)-(x+4)(x-7)=5-x
k) (4x-5)(x+1)-4(x-1)(x+1)=7
l) (3x-4)(x-2)=3x(x-9)-3
Rút gọn:
\(C=\dfrac{\sqrt{x+2-4\sqrt{x-2}}+\sqrt{x+2+4\sqrt{x-2}}}{\sqrt{\dfrac{4}{x^2}-\dfrac{4}{x}+1}}\)
$$ \frac{x^4-(x-1)^2}{(x^2+1)^2-x^2}+\frac{x^2-(x^2-1)^2}{x^2*(x+1)^2-1}+\frac{x^2*(x-1)^2-1}{x^4-(x+1)^2} $$
