a) x2 + 2x + 1 = x2 + 2.x.1+ 12 = ( x + 1)2
b) 9x2 + y2 + 6xy = (3x)2 + 2.3.x.y + y2 = (3x + y)2
c) 25a2 + 4b2 – 20ab = (5a)2 – 2.5.a.2b. + (2b)2 = (5a – 2b)2
Hoặc 25a2 + 4b2 – 20ab = (2b)2 – 2.2b.5a. + (5a)2 = (2b – 5a)2
d) x2 – x + \(\dfrac{1}{4}\) = x2 – 2.x. \(\dfrac{1}{2}\) + ( \(\dfrac{1}{2}\))22 = ( x - \(\dfrac{1}{2}\) )2
Hoặc x2 – x + \(\dfrac{1}{4}\) = \(\dfrac{1}{4}\) - x + x2 = (\(\dfrac{1}{2}\))2 – 2. \(\dfrac{1}{2}\).x + x2 = (\(\dfrac{1}{2}\) - x)2
a) x2 + 2x + 1 = x2+ 2 . x . 1 + 12
= (x + 1)2
b) 9x2 + y2+ 6xy = (3x)2 + 2 . 3 . x . y + y2 = (3x + y)2
c) 25a2 + 4b2– 20ab = (5a)2 – 2 . 5a . 2b + (2b)2 = (5a – 2b)2
Hoặc 25a2 + 4b2 – 20ab = (2b)2 – 2 . 2b . 5a + (5a)2 = (2b – 5a)2
d) x2 – x + 1414 = x2 – 2 . x . 1212 + (12)2(12)2= (x−12)2(x−12)2
Hoặc x2 – x + 1414 = 1414 - x + x2 = (12)2(12)2 - 2 . 1212 . x + x2 = (12−x)2
a) x2 + 2x + 1 = x2+ 2 . x . 1 + 12
= (x + 1)2
b) 9x2 + y2+ 6xy = (3x)2 + 2 . 3 . x . y + y2 = (3x + y)2
c) 25a2 + 4b2– 20ab = (5a)2 – 2 . 5a . 2b + (2b)2 = (5a – 2b)2
Hoặc 25a2 + 4b2 – 20ab = (2b)2 – 2 . 2b . 5a + (5a)2 = (2b – 5a)2
d) x2 – x + 1414 = x2 – 2 . x . 1212 + (12)2(12)2= (x−12)2(x−12)2
Hoặc x2 – x + 1414 = 1414 - x + x2 = (12)2(12)2 - 2 . 1212 . x + x2 = (12−x)2
Chúc bạn học tốt
a) x2+2x+1=x2+2.x.1+12x2+2x+1=x2+2.x.1+12=(x+1)2=(x+1)2
b) 9x2+y2+6xy=9x2+6xy+y29x2+y2+6xy=9x2+6xy+y2=(3x)2+2.3.x.y+y2=(3x+y)2=(3x)2+2.3.x.y+y2=(3x+y)2
c) 25a2+4b2−20ab25a2+4b2−20ab
=25a2−20ab+4b2=25a2−20ab+4b2
=(5a)2−2.5a.2b+(2b)2=(5a−2b)2=(5a)2−2.5a.2b+(2b)2=(5a−2b)2
Hoặc
25a2+4b2−20ab25a2+4b2−20ab
=4b2−20ab+25a2=4b2−20ab+25a2
=(2b)2−2.2b.5a+(5a)2=(2b−5a)2=(2b)2−2.2b.5a+(5a)2=(2b−5a)2
d) x2−x+14=x2−2.x.12+(12)2x2−x+14=x2−2.x.12+(12)2=(x−12)2=(x−12)2
Hoặc
x2−x+14=14−x+x2x2−x+14=14−x+x2
=(12)2−2.12.x+x2=(12−x)2
a) x2+2x+1x2+2x+1
=x2+2.x.1+12=(x+1)2=x2+2.x.1+12=(x+1)2
b) 9x2+y2+6xy9x2+y2+6xy
=9x2+6xy+y2=9x2+6xy+y2=(3x)2+2.3.x.y+y2=(3x+y)2=(3x)2+2.3.x.y+y2=(3x+y)2
c) 25a2+4b2−20ab25a2+4b2−20ab
=25a2−20ab+4b2=25a2−20ab+4b2
=(5a)2−2.5a.2b+(2b)2=(5a)2−2.5a.2b+(2b)2
=(5a−2b)2=(5a−2b)2
Hoặc
25a2+4b2−20ab25a2+4b2−20ab
=4b2−20ab+25a2=4b2−20ab+25a2
=(2b)2−2.2b.5a+(5a)2=(2b)2−2.2b.5a+(5a)2
=(2b−5a)2=(2b−5a)2
d) x2−x+14x2−x+14
=x2−2.x.12+(12)2=x2−2.x.12+(12)2
=(x−12)2=(x−12)2
Hoặc
x2−x+14=14−x+x2x2−x+14=14−x+x2
=(12)2−2.12.x+x2=(12−x)2
