Ta có: \(\left(2x-1\right)^3-\left(3x^2-1\right)\left(x-2\right)+\left(x+3\right)^3\)
\(=8x^3-12x^2+6x-1-\left(3x^3-6x^2-x+2\right)+x^3+9x^2+27x+27\)
\(=9x^3-3x^2+33x+26-3x^3+6x^2+x-2\)
\(=6x^3+3x^2+34x+24\)
Rut gon cac bieu thuc sau
b,P=\(\left(3x+1\right)^2-2\left(1+3x\right)\left(3x+5\right)+\left(3x+5\right)^2\)
T=(3+1)\(\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\)
Rut gon va tinh gia tri bieu thuc
A= (x-4).(x-2)-(x-1).(x-3) tại x= \(1\dfrac{3}{4}\)
rut gon bieu thuc
((x^2+a)(1+a)+a^2x^2+1):((x^2-a)(1-a)+a^2x^2+1)
cm ptrinh treb ko phu thuoc vao x
bai 1
a = (3x / 2x + 4 ) + (x +3 /x ^ 2 - 4 )
a . tim x de gia tri phan thuc a duoc xac dinh
b. rut gon a
c. tinh gia trin cua a khi x bang -3
d . tim gia tri cua x de phan thuc co gia tri bang 2
rut gon bieu thuc sau : P=2(x+y)(x-y)-(x-y)^2+(x+y)^2-4y^2
Bai 1: Cho bt
P=(\(\dfrac{x-2}{x^2-1}\)-\(\dfrac{x+2}{x^2+2x+1}\)).(\(\dfrac{1-x^2}{2}\))2
a, Rut gon P
b, Tim x de \(\dfrac{P-4}{5}\)=x
Bai 2:Chung minh bieu thuc A=\(\dfrac{3}{2}\)-\(\dfrac{x}{x^2+x+1}\) luon duong voi moi x
rut gon phan thuc:
1 \(\dfrac{x^2-18x-19}{x^2-1}\)
2 \(\dfrac{x\left(4x^2-8x+4\right)}{2x^3-2x^2}\)
Rut gon bieu thuc
A=(x+1)\(\left(x^2+1\right)\left(x^4+1\right)...\left(x^{256}+1\right)+1\)
viet cac bieu thuc sau duoi dang tich:
a, 27x\(^3\)-27x\(^2\)+3x+1
b,x\(^3\)-3x\(^2\)+3x-1
c,\(\dfrac{1}{27}\)+x\(^3\)
d, 0,001-1000x\(^3\)
