Giải thích các bước giải:
a/ $(-3x+5)^2=(5-3x)^2=5^2-2.5.3x+(3x)^2=25-30x+9x^2$
b/ $(2x+\dfrac{1}{2})^2=(2x)^2+2.2x.\dfrac{1}{2}+(\dfrac{1}{2})^2=4x^2+2x+\dfrac{1}{4}$
c/ $(2x-1)^2-(x-3)^2$
$=(2x)^2-2.2x+1-(x^2-2.3x+3^2)$
$=4x^2-4x+1-x^2+6x-9$
$=3x^2+2x-8$
d/ $(3x^2-\dfrac{1}{2^3})+(x^3+\dfrac{1}{4})^2$
$=3x^2-\dfrac{1}{8}+x^6+\dfrac{1}{2}.x^3+\dfrac{1}{16}$
$=x^6+\dfrac{1}{2}x^3+3x^2-\dfrac{1}{16}$
e/ $(a-3)+(a+1)^3=a-3+a^3+3a^2+3a+1=a^3+3a^2+4a-2$
Chúc bạn học tốt !!!
