Question

  

Answer 1

Bài 14:

a) \(x^2+6x+9\)

\(=x^2+2\cdot3\cdot x+3^2\)

\(=\left(x+3\right)^2\)

b) \(x^2-10x+25\)

\(=x^2-2\cdot5\cdot x+5^2\)

\(=\left(x-5\right)^2\)

c) \(4x^2+4x+1\)

\(=\left(2x\right)^2+2\cdot2x\cdot1+1^2\)

\(=\left(2x+1\right)^2\)

d) \(9x^2-12x+4\)

\(=\left(3x\right)^{^2}-2\cdot3x\cdot2+2^2\)

\(=\left(3x-2\right)^2\)

e) \(x^2+2xy+y^2\)

\(=\left(x+y\right)^2\)

f) \(9x^2+24x+16\)

\(=\left(3x\right)^2+2\cdot3x\cdot4+4^2\)

\(=\left(3x+4\right)^2\)

h) \(x^2-x+\dfrac{1}{4}\)

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

\(=\left(x-\dfrac{1}{2}\right)^2\)

i) \(\left(x+y\right)^2-2\cdot\left(x+y\right)\cdot z+z^2\)

\(=\left[\left(x+y\right)-z\right]^2\)

\(=\left(x+y-z\right)^2\)