Question

cho x+y=5 tính Q= x³+y³-2x²-2y²-3xy(x+y)-4xy+3(x+y)+10

Answer 1

\(Q=x^3+y^3-2x^2-2y^2-3xy\left(x+y\right)-4xy+3\left(x+y\right)+10\)

\(Q=\left(x^3+y^3\right)-2\left(x^2+y^2\right)+3xy\left(x+y\right)-4xy+3\left(x+y\right)+10\)

\(Q=\left(x+y\right)^3-3xy\left(x+y\right)-2(\left(x+y\right)^2-2xy)+3xy\left(x+y\right)-4xy+3\left(x+y\right)+10\)

\(Q=\left(x+y\right)^3-3xy\left(x+y\right)-2\left(x+y\right)^2+4xy+3xy\left(x+y\right)-4xy+3\left(x+y\right)+10\)

\(Q=\left(5\right)^3-3xy\left(5\right)-2\left(5\right)^2+4xy+3xy\left(5\right)-4xy+3\left(5\right)+10\)

\(Q=125-15xy-50+4xy+15xy-4xy+15+10\)

\(Q=100\)

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