Question

Mọi người giúp mình với ạ

Answer 1

a) \(y^2+49-14y\)

\(=y^2-14y+49\)

\(=y^2-2\cdot7\cdot y+7^2\)

\(=\left(y-7\right)^2\)

b) \(a^2+4b^2-4ab\)

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

\(=a^2-2\cdot2b\cdot a+\left(2b\right)^2\)

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

c) \(y^2+y+\dfrac{1}{4}\)

\(=y^2+2\cdot\dfrac{1}{2}\cdot y+\left(\dfrac{1}{2}\right)^2\)

\(=\left(y+\dfrac{1}{2}\right)^2\)