Toán Lớp 8: Phân tích các đa thức thành nhân tử:
a) 4x^2+16x+13
b) x^2+x-56
c) x^2-x-72
d) x^2+6x-4y^2+9
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Toán Lớp 8: Phân tích các đa thức thành nhân tử:
a) 4x^2+16x+13
b) x^2+x-56
c) x^2-x-72
d) x^2+6x-4y^2+9
Comments ( 2 )
$\text{a) 4x² + 16x + 12}$
$\text{= 4x² + 4x + 12x + 12}$
$\text{= 4x(x + 1) + 12(x + 1)}$
$\text{= (x + 1)(4x + 12)}$
$\text{= (x + 1)(x + 3)4}$
$\text{b) x² + x – 56}$
$\text{= x² + 8x – 7x – 56}$
$\text{= x(x + 8) – 7(x + 8)}$
$\text{= (x + 8)(x – 7)}$
$\text{c) x² – x – 72}$
$\text{= x² – 9x + 8x – 72}$
$\text{= x(x – 9) + 8(x – 9)}$
$\text{= (x – 9)(x + 8)}$
$\text{d) x² + 6x – 4y² + 9}$
$\text{= (x² + 6x + 9) – 4y²}$
$\text{= (x + 3)² – (2y)²}$
$\text{= (x + 3 – 2y)(x + 3 + 2y)}$
$\textit{Ha1zzz}$
a) 4x^2+16x+12
4(x^2 +4x+3)=0
x^2 +4x +3 =0
4^2 -4(1.3)=4
x=-3
x=-1
b) x^2+x-56
x=-8 , x= 7
c)x^2-x-72
x= -8,x=9