\(ab-ac+bc=c^2-1\)
\(ab-ac+bc-c^2=-1\)
\(a\left(b-c\right)+c\left(b-c\right)=-1\)
\(\Leftrightarrow\left(a+c\right)\left(b-c\right)=-1\)
=> a + c = 1 thì b - c = - 1; a + c = - 1 thì b - c = 1 => a + c và b - c đối nhau
\(\Rightarrow a+c=-\left(b-c\right)\)
\(a+c=-b+c\)
\(\Rightarrow a=-b\)
\(\Rightarrow B=\frac{a}{b}=-1\)
tinh gia tri bieu thuc
/a+b-c/
biet A= -5 ; B=2;C=1
BIET / LA GIA TRI tuyet doi
cho a,b,c khac 0 thoai man ab/a+b=bc/b+c=ca/c+a
tinh gia tri bieu thuc m=ab+bc+ca/a^2+b^2+c^2
Cho bieu thuc A = \(^{x2+4x+3}\)
a Tinh gia tri bieu thuc tai x= \(\frac{-1}{2}\)
b Tinh gia tri x de bieu thuc A bang 0
cho cac so a,b,c va thoa man \(\frac{ab}{a+b}=\frac{1}{3},\frac{bc}{b+c}=\frac{1}{4},\frac{ca}{c+a}=\frac{1}{5}\)Tinh gia tri bieu thuc P=\(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\)
Cho 3 so a,b,c khac 0 thoa man ab/a+b=bc/b+c=ca/c+a
Tinh gia tri cua bieu thuc M=ab+bc+ca/a^2+b^2+c^2
Cho cac so a,b,c,d thoa man a+b=67,c+d=30 tinh gia tri bieu thuc P=ad+bc+ac+bd
Biet (a+1)(b+1) = 551 . Khi do gia tri bieu thuc ab+a+b = ......
cho biet x=-2 la nghiem cua da thuc p(x)=ax+b tinh gia tri bieu thuc 2011a+b/3a-b
Cho a.b,c la 3 so khac 0 thoa man : ab + a + b / a + b = bc + b + c / b + c = ca + c + a/ c + a ( voi gia thiet cac ti so deu co nghia)
Tinh gia tri bieu thuc M = ab+bc+ca+2017/ a^2 + b^2 + c^2 + 2017
