C1: \(B=x^3+3xy+y^3\)
\(=\left(x+y\right)^3-3xy\left(x+y\right)+3xy\)
\(=\left(x+y\right)^3-3xy\left(x+y-1\right)\)
Thay \(x+y=1\)ta được:
\(B=1^3-3xy\left(1-1\right)=1\)
C2: \(x+y=1\)\(\Rightarrow\)\(x=1-y\)
\(B=x^3+3xy+y^3=\left(1-y\right)^3+3\left(1-y\right)y+y^3\)
\(=1-3y+3y^2-y^3+3y-3y^2+y^3=1\)
cho x+y =1 . tinh gia tri cua bieu thuc A=x^3+y^3+3xy
chox-y=1. tinh gia tri cua bieu thuc B=x^3-y^3-3xy
cho x+y=1 . tinh gia tri cua bieu thuc C=x^3+y^3+3xy(x^2+y^2)+6x^2*y^2(x+y)
tinh gia tri bieu thuc
C=x^3+y^3+3xy(x^2+y^2)+6x^2y^2(x+y) với x+y=1
nhanh nha mik tick cho
Cho x+y=2, tinh gia tri cua bieu thuc:
M=3(x^2+y^2)-(x^3+y^3)+1
Bai 2:Cho a+b=5,tinh gia tri bieu thuc:
M=3a^2-2a+3b^2-2b+6ab+100
Cho x - y = 7 . Tinh gia tri cua bieu thuc
a) M = x3 - 3xy . ( x - y ) - y3 - x2 + 2xy - y2
b) N = x2 . ( x + 1 ) - y2 . ( y - 1 ) + xy - 3xy . ( x - y + 1 ) - 95
Cho phan thuc B=(3\y+3)+(1\y-3)-(18\9-y2)
a)Tim dieu kien cua y de gia tri cua bieu thuc B duoc xac dinh
b)Rut gon bieu thuc B
c)Tinh gia tri cua B de B co gia tri nguyen
Cho bieu thuc A = ( 1/ x^2 - x + 1/x-1):x+1/x^2 -2x +1 ( x khac 0;1;-1)
a) Rut gon bieu thuc A
b) Tinh gia tri bieu thuc A khi x=2014/2013
c)Tim dieu kien cua x de A co gia tri lon hon 1
1) Cho bieu thuc A=\(3+\frac{2}{x-1}\). Tinh gia tri cua bieu thuc A khi |2x-3|=1
2) Rut gon bieu thuc B=\(\frac{x}{x-1}\)-\(\frac{x-5}{x+1}\)-\(\frac{3-x}{1-x^2}\)
3) Tim cac gia tri nguyen cua x de bieu thuc \(\frac{B}{A}\)co gia tri nguyen duong
Cho x^2+y^2= 1. Tinh gia tri bieu thuc: 2(x^6+y^6)-3(x^4+y^4)?
cho 2 bieu thuc A=x+x^2/2-x va B=2x/x+1+3/x-2-2x^2+1/x^2-x-2 a, tinh gia tri cua A khi /2x-3/=1 b,tim dieu kien xac dinh va rut gon bieu thuc B c,tim so nguyen x de P=A.B dat gia tri lon nhat
mk dang can gap
