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X2+4xy-21y2=(x2+4xy+4y2)-25y2=(x+2)2-(5y)2=(x+2-5y)(x+2+5y)
5x2+6xy+y2=9x2+6xy+y2-4x2=(3x+y)2-4x2=(3x+y+2x)(3x+y-2x)
(x-y)2+4(x-y)-12=(x-y+2)2-16=(x-y+2+4)(x-y+2-4)
x2-7xy+10y2=x2-7xy+\(\frac{49y^2}{4}-\frac{9y^2}{4}\)= \(\left(x-\frac{7}{2}\right)^2-\left(\frac{3y}{2}\right)^2\)=\(\left(x-\frac{7}{2}-\frac{3y}{2}\right)\left(x-\frac{7}{2}+\frac{3y}{2}\right)\)
x2+2xy-15y2=(x+y)2-16y2=(x+y-4y)(x+y+4y
a)3x2-5x-2=3x2-6x+x-2
=3x(x-2)+(x-2)
=(3x+1)(x-2)
b)x2-7xy-10y2=x2-2xy-5xy-10y2
=x(x-2y)-5y(x-2y)
=(x-5y)(x-2y)
c)c) x2 +4xy-21y2=x2+7xy-3xy-21y2
=x(x+7y)-3y(x+7y)
=(x-3y)(x+7y)
d) 5x2 +6xy+y2=5x2+5xy+xy+y2
=5x(x+y)+y(x+y)
=(5x+y)(x+y)
e) x2 +2xy-15y2=x2+5xy-3xy-15y2
=x(x+5y)-3y(x+5y)
=(x-3y)(x+5y)
CHÚC BẠN HỌC TỐT
a) \(x^2+4xy-21y^2=x^2-3xy+7xy-21y^2=x\left(x-3y\right)+7y\left(x-3y\right)\)\(=\left(x-3y\right)\left(x+7y\right)\)
b)\(5x^2+6xy+y^2\)
=\(5x^2+5xy+xy+y^2\)
=\(5x^{ }\left(x+y\right)+y\left(x+y\right)\)
=\(\left(5x+y\right)\left(x+y\right)\)
c) \(x^2-7xy+10y^2\)
\(=\left(x^2-2xy\right)\left(5xy-10y^2\right)\)
\(=x\left(x-2y\right)-5y\left(x-2y\right)\)
\(=\left(x-5y\right)\left(x-2y\right)\)
d)\(x^2+2xy-15y^2\)
\(=x^2+2xy+y^2-16y^2\)
\(\left(x+y\right)^2-\left(4y\right)^2\)
\(=\left(x-3y\right)\left(x+5y\right)\)
a) 3x2 +9x - 30
= 3(x2 + 3x -10) = 3[(x2 -2x)+(5x-10)]
= 3(x-2)(x+5)
b) x2 -9x + 18 = (x2 - 3x) - (6x-18)
= (x-3)(x-6)
c) x2 -7x +12 = (x2 -3x)-(4x-12)
= (x-3)(x-4)
d) x2 + 4xy -21y2 = (x2 -3xy)+(7xy - 21y2)
= (x-3y)(x+7y)
e) 5x2 + 6xy +y2
= (5x2 + 5xy)+(xy+y2)
= (x+y)(5x+y)
f) x2 +2xy-15y2 = (x2 - 3xy)+(5xy-15y2)
= (x-3y)(x+5y)
g) x2 -7xy+10y2 = (x2 - 2xy)-(5xy-10y2)
= (x-2y)(x-5y)
h) 4x4 +1 = [(2x2)2 + 4x2 + 1 ] - 4x2
= (2x2 +1)2 -(2x)2
= (2x2 + 1-2x)(2x2 +1+2x)
i) x4 + 324 = [x4 + 36x2 + 182] - 36x2
= (x2 + 18)2 - (6x)2
= (x2 -6x +18)(x2 +6x+18)
3x2+9x-30
=3(x2+3x-10)
=3(x2+5x-2x-10)
=3[(x2+5x)-(2x+10)]
=3[x(x+5)+2(x+5)]
=3(x+5)(x+2)
a)\(9x^2y^3-3x^4y^2-6x^3y^2+18xy^4=3xy^2\left(3xy-x^3-2x^2+6y^2\right)\)
b)\(a^3x^2y^2-\frac{5}{2}a^3x^4+\frac{3}{2}a^4x^2y=a^3x^2\left(y^2-\frac{5}{2}x^2+\frac{3}{2}ay\right)\)
c)\(x^2+4xy-21y^2=\left(x^2+4xy+4y^2\right)-25y^2=\left(x+2y\right)^2-\left(5y\right)^2=\left(x+2y-5y\right)\left(x+2y+5y\right)=\left(x-3y\right)\left(x+7y\right)\)d)\(2x^4+4=2\left(x^4+4\right)=2\left(x^4+4x^2+4-4x^2\right)=2\left[\left(x^2+2\right)^2-\left(2x\right)^2\right]=2\left(x^2-2x+2\right)\left(x^2+2x+2\right)\)
a, 3x^2 + 13x + 10
= 3x^2 + 3x + 10x + 10
= 3x(x + 1) + 10(x + 1)
= (3x + 10)(x + 1)
b, x^2 - 10x + 21
= x^2 - 3x - 7x + 21
= x(x - 3) - 7(x - 3)
= (x - 7)(x - 3)
c, 6x^2 - 5x + 1
= 6x^2 - 3x - 2x + 1
= 3x(2x - 1) - (2x - 1)
= (3x - 1)(2x - 1)
Bạn đăng 1 lần nhiều bài như vậy làm người khác nản lắm đấy =) đơn giản bài rất dài mà mik cx ko chắc là bản thân mik có đc k hay ko nên phải nản vậy thôi :)
1a)\(3x^2+13x+10=3x^2+3x+10x+10\)
\(3x\left(x+1\right)+10\left(x+1\right)=\left(3x+10\right)\left(x+1\right)\)
b)\(x^2-10x+21=x^2-3x-7x+21\)
\(=x\left(x-3\right)-7\left(x-3\right)=\left(x-7\right)\left(x-3\right)\)
c)\(6x^2-5x+1=6x^2-3x-2x+1\)
\(=3x\left(2x-1\right)-\left(2x-1\right)=\left(3x-1\right)\left(2x-1\right)\)
a) \(x^2-5x+6=x^2-2x-3x+6=\left(x-2\right)\left(x-3\right)\)
b)\(3x^2+9x-30=3x^2-6x+15x-30=3\left(x-2\right)\left(x+5\right)\)
c)\(x^2-7x+12=x^2-3x-4x+12=\left(x-3\right)\left(x-4\right)\)
d)\(x^2-7x+10=x^2-2x-5x+10=\left(x-2\right)\left(x-5\right)\)
a) \(x^2-5x+6=x^2-2x-3x+6=\left(x^2-2x\right)-\left(3x-6\right)\)
\(=x\left(x-2\right)-3\left(x-2\right)=\left(x-2\right)\left(x-3\right)\)
b) \(3x^2+9x-30=3\left(x^2+3x-10\right)=3\left(x^2-2x+5x-10\right)\)
\(=3\left[\left(x^2-2x\right)+\left(5x-10\right)\right]=3\left[x\left(x-2\right)+5\left(x-2\right)\right]\)
\(=3\left(x-2\right)\left(x+5\right)\)
c) \(x^2-7x+12=x^2-3x-4x+12=\left(x^2-3x\right)-\left(4x-12\right)\)
\(=x\left(x-3\right)-4\left(x-3\right)=\left(x-3\right)\left(x-4\right)\)
d) \(x^2-7x+10=x^2-2x-5x+10=\left(x^2-2x\right)-\left(5x-10\right)\)
\(=x\left(x-2\right)-5\left(x-2\right)=\left(x-2\right)\left(x-5\right)\)
Ta có : 5x2 + 6xy + y2
= 5x2 + 5xy + xy + y2
= 5x(x + y) + y(x + y)
= (5x + y)(x + y)
a, \(x^2+4xy-21y^2\)
\(=x^2-3xy+7xy-21y^2\)
\(=x\left(x-3y\right)+7y\left(x-3y\right)\)
\(=\left(x-3y\right)\left(x+7y\right)\)
b, \(5x^2+6xy+y^2\)
\(=5x^2+5xy+xy+y^2\)
\(=5x\left(x+y\right)+y\left(x+y\right)\)
\(=\left(x+y\right)\left(5x+y\right)\)
c, \(x^2+4xy-21y^2\)
(giống câu a)
d, \(x^2-4xy+10y^2\)
(bạn xem lại đề nhá)
a, \(x^2+4xy-21y^2\)
= \(\left(x-3y\right).\left(x+7y\right)\)
b, \(5x^2+6xy+y^2\)
= \(\left(x+y\right).\left(5x+y\right)\)
c, \(x^2+4xy-21y^2\)
= \(\left(x-3y\right).\left(x+7y\right)\)
d,\(x^2-4xy+10y^2\)
= \(x^2-2xy-2xy+10y^2\)
= \(x.\left(x-2y\right)-2y.\left(x+5y\right)\)
= ....................