` c) ` ` x^4 + 6x^2 + 3^2 = (x^2 + 3)^2 `
` d) ` ` 25x^2 - 30x + 3^2 = (5x - 3)^2 `
` e) ` ` 9x^2 + 18x + 3^2 = (3x + 3)^2 ` hay ` 9(x + 2)^2 `
` f) ` ` 1/4 x^2 + 7/2 x + (7/2)^2 = (1/2 x + 7/2)^2 `
` h) ` ` (5/2)^2 + 5x + x^2 = (5/2 + x)^2 `
` g) ` ` (\frac{11}{2})^2 - 11x + x^2 = (\frac{11}{2} - x)^2 `
Áp dụng hằng đẳng thức:
` a^2 + 2ab + b^2 = (a + b)^2 `
` a^2 - 2ab + b^2 = (a - b)^2 `
