Question

Phân tích thành nhân tử :

a) \(x^2-7\)

b) \(x^2-2\sqrt{2}x+2\)

c) \(x^2+2\sqrt{13}x+13\)

Answer 1

a, \(x^2-7=x^2-\left(\sqrt{7}\right)^2=\left(x-\sqrt{7}\right)\left(x+\sqrt{7}\right)\)

b, \(x^2-2\sqrt{2}x+2=x^2-2\sqrt{2}x+\left(\sqrt{2}\right)^2=\left(x-\sqrt{2}\right)^2\)

c, \(x^2+2\sqrt{13}x+13=x^2+2\sqrt{13}x+\left(\sqrt{13}\right)^2=\left(x+\sqrt{13}\right)^2\)

Answer 2

a) \(x^2-7=x^2-\left(\sqrt{7}\right)^2=\left(x-\sqrt{7}\right)\left(x+\sqrt{7}\right)\)

b) \(x^2-2\sqrt{2}x+2=x^2-2.x.\sqrt{2}+\left(\sqrt{2}\right)^2=\left(x-\sqrt{2}\right)^2\)

c) \(x^2+2\sqrt{13}x+13=x^2+2.x.\sqrt{13}+\left(\sqrt{13}\right)^2=\left(x+\sqrt{13}\right)^2\)