Viết bằng tổng hoặc hiệu bình phương:
a, $x^{2}$ + 2x + 1
b, $x^{2}$ – 4x + 4
c, 4x$x^{2}$ – 4x + 1
d, 9$x^{2}$ + 6x + 1
e, $x^{2}$ – x + $\frac{1}{4}$
g, 25$x^{2}$ – 10x + 1
Viết bằng tổng hoặc hiệu bình phương:
a, $x^{2}$ + 2x + 1
b, $x^{2}$ – 4x + 4
c, 4x$x^{2}$ – 4x + 1
d, 9$x^{2}$ + 6x + 1
e, $x^{2}$ – x + $\frac{1}{4}$
g, 25$x^{2}$ – 10x + 1
Đáp án:
$\text{a, x² + 2x +1 = (x+1)² }$
$\text{b, x² -4x +4 = (x-2)² }$
$\text{c) 4x² -4x +1 = (2x-1)² }$
$\text{d) 9x² + 6x + 1 = (3x+1)² }$
$\text{e) . x² – x + $\dfrac{1}{4}$ = (x-$\dfrac{1}{2}$)² }$
$\text{g. 25x² – 10x + 1 = (5x-1)² }$
a, $x^2+2x+1= x^2+2x.1+1^2= (x+1)^2$
b, $x^2-4x+4= x^2-2.x.2+2^2= (x-2)^2$
c, $4x^2-4x+1= (2x)^2-2.2x.1+1^2= (2x-1)^2$
d, $9x^2+6x+1= (3x)^2+2.3x.2+1^2= (3x+1)^2$
e, $x^2-x+\frac{1}{4}=x^2-2x.\frac{1}{2}+(\frac{1}{2})^2= (x-\frac{1}{2})^2$
f, $25x^2-10x+1= (5x)^2-2.5x.1+1^2= (5x-1)^2$