Question

viết dưới dạng tổng 2 bình phương

\(a^2-4ab+5b^2-4bc+4c^2\)

Answer 1

a² - 4ab + 5b² - 4bc + 4c²

= a² - 4ab + 4b² + 4c² - 4bc + b²

= (a - 2b)² + (2c - b)²

Answer 2

\(a^2-4ab+5b^2-4bc+4c^2\)

\(=a^2-4ab+4b^2+b^2-4bc+4c^2\)

\(=a^2-2.a.2b+\left(2b\right)^2+b^2-2.b.2c+\left(2c\right)^2\)

\(=\left(a-2b\right)^2+\left(b-2c\right)^2\)