Toán Lớp 8: phân tích đa thức thành nhân tử 33, $x^{2}$ +14x +49 34, $x^{2}$ +12x +36 35, 4$x^{2}$ +12x +9 36 9$x^{2}$ -12x +4 37, 16$x^{2}$ -8

Question

Toán Lớp 8:  phân tích đa thức thành nhân tử  33,  $x^{2}$ +14x +49 34,  $x^{2}$ +12x +36 35,  4$x^{2}$ +12x +9 36 9$x^{2}$ -12x +4 37, 16$x^{2}$ -8x +1 38,  4$x^{4}$ -20$x^{2}$ +25

ankim · Answer

Giải đáp:   $33) x&sup2;+14x+49=(x+7)&sup2;$   $34) x&sup2;+12x+36=(x+6)&sup2;$   $35) 4x&sup2;+12x+9=(2x+3)&sup2;$   $36) 9x&sup2;-12x+4=(3x+2)&sup2;$   $37) 16x&sup2;-8x+1=(4x+1)&sup2;$   $38) 4x&sup2;-20x&sup2;+25$   $=(2x&sup2;)&sup2;-2.2x&sup2;.5+5&sup2;$   $=(2x&sup2;-5)&sup2;$         Ch&uacute;c bn hc tốt   ????

ngoclandiep · Answer

33. x^2+14x+49     = x^2+2.7x+7^2     = (x+7)^2     34. x^2+12x+36     = x^2+2.6x+6^2     = (x+6)^2     35. 4x^2+12x+9     = (2x)^2+2.3.2x+3^2     = (2x+3)^2     36. 9x^2-12x+4     = (3x)^2-2.2.3x+2^2     = (3x-2)^2     37. 16x^2-8x+1     = (4x)^2-2.1.4x+1^2     = (4x-1)^2     38. 4x^4-20x^2+25     = (2x^2)^2-2.5.2x^2+5^2     = (2x^2-5)^2