A = x ( x + y ) - y ( x + y )
A = ( x + y ) ( x - y )
A = x\(^2\) - y\(^2\)
Tại x = \(\dfrac{-1}{2}\) và y = -2 ta có
\(\left(\dfrac{-1}{2}\right)^2-\left(-2\right)^2\) \(=\) \(\dfrac{-15}{4}\)
\(A=x\left(x+y\right)-y\left(x+y\right)\)
\(=\left(x+y\right)\left(x-y\right)\)
\(=x^2-y^2\)
Thay \(x=-\dfrac{1}{2}\) và \(y=-2\) vào biểu thức \(A\), ta có:
\(A=\left(-\dfrac{1}{2}\right)^2-\left(-2\right)^2\)
\(=\dfrac{1}{4}-4\)
\(=-\dfrac{15}{4}\)
A = x ( x + y ) - y ( x + y )
A = ( x + y ) ( x - y )
A = x2 - y2
Thay x== (−1/2)2−(−2)2
=
\(A=x\left(x+y\right)-y\left(x+y\right)\)
\(=\left(x+y\right)\left(x-y\right)\)
\(=x^2-y^2\)
\(=\dfrac{1}{4}-4=\dfrac{-15}{4}\)