Ta có:\(m=\dfrac{b+c}{a}+\dfrac{c+a}{b}+\dfrac{a+b}{c}\)
\(m=\left(\dfrac{b+c}{a}+1\right)+\left(\dfrac{c+a}{b}+1\right)+\left(\dfrac{a+b}{c}+1\right)-3\)
\(m=\dfrac{a+b+c}{a}+\dfrac{a+b+c}{b}+\dfrac{a+b+c}{c}-3\)
\(m=\left(a+b+c\right)\left(\dfrac{1}{a}+\dfrac{1}{b}+\dfrac{1}{c}\right)-3\)
\(m=0-3=-3\)
cho bieu thuc A=[x+2/x^2-x+x-2/x^2+x].x^2-1/x^2+2
a) tim dieu kien cua x de gia tri cua bieu thuc A duoc xac dinh
b) tinh gia tri cua bieu thuc A voi x = -200
cho a,b,c la ba so doi mot khac nhau thoa man (a+b+c)2=a2+b2+c2
tinh gia tri cua bieu thuc P=a2/(a2+2bc)+b2/(b2+2ac)+c2/(c2+2ab)
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
Cho a,b,c thoa man \(\dfrac{1}{a}+\dfrac{1}{b}+\dfrac{1}{c}=\dfrac{1}{a+b+c}\)
Tinh GT cua bieu thuc A=\(\left(a^3+b^3\right)\left(b^3+c^3\right)\left(c^3+a^3\right)\)
tinh gia tri cua bieu thuc:
A=x^2+12x+36 tai x=64
B=x^2+4xy+4y^2 khi biet x=2,8; y=3,6
C=(3x-7)^2+10(3x-7)+25 biet x=16
D=8x^3-12x^2+6x-1 tai x=\(\dfrac{-1}{2}\)
tinh nhanh gia tri cua bieu thuc sau voi a=1982
M=(a+4)^2+2(a+4)(6-a)+(6-a)^2
tinh gia tri cua cac bieu thuc sau:
a,x(x-6)-y(6-x) tai x=2006,y=2002
b,5x(x-y)-y(x-y) tai x=60,y=5
cho x=(b2+c2-a2)/2bc;y=(a2-(b-c)2)/((b+c)2-a2) tinh gia tri cua P=xy+x+y+2017
cho 3 số x,y,z khác 0 thỏa mãn 1/x+1/y+1/z=0 gia tri bieu thuc K=(xy/z^2+yz/x^2+xz/y^2-2)^2017 là
