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a) \(25x^2-20xy+4y^2\)
\(=\left(5x\right)^2-2.5x.2y+\left(2y\right)^2\)
\(=\left(5x-2y\right)^2\)
b) \(4x^2+9+12x\)
\(=\left(2x\right)^2+3^2+2.2x.3\)
\(=\left(2x+3\right)^2\)
c) \(\frac{1}{4}+3x+9x^2\)
\(=\left(\frac{1}{2}\right)^2+2.\frac{1}{2}.3x+\left(3x\right)^2\)
\(=\left(\frac{1}{2}+3x\right)^2\)
d) \(-6xy+x^2+9y^2\)
\(=x^2-6xy+9y^2\)
\(=x^2-2.x.3y+\left(3y\right)^2\)
\(=\left(x-3y\right)^2\)
a,9a2-30a+25
=(3a)2-30a+52
=(3a-5)2
b,1+4x+4x2
=4x2+4x+1
=(2x)2+4x+12
=(2x+1)2
c,a2+16+8a
=a2+8a+16
=a2+8a+42
=(a+2)2
d,25x2+4y2-20xy
=25x2-20xy+4y2
=(5x)2-20xy+(2y)2
=(5x-2y)2
a) \(a^2-2a+1=a^2-2\times a\times1+1^2=\left(a-1\right)^2\)
b) sửa lại đề thành \(1-4x+4x^2\)
\(1-4x+4x^2=1^2-2\times2x\times1+\left(2x\right)^2=\left(1-2x\right)^2\)
c) bạn xem lại đề câu C nha mik làm lun
d) \(25x^2-20xy+4y^2=\left(5x\right)^2-2\times5x\times2y+\left(2y\right)^2=\left(5x-2y\right)^2\)
a) \(a^2-2a+1\)
\(=\left(a-1\right)^2\)
b) Sửa đề \(1-4x+4x^2\)
\(=\left(2x\right)^2-2.2x+1\)
\(=\left(2x-1\right)^2\)
c) \(a^2+9-6x\)
\(=a^2-2.x.3+3^2\)
\(=\left(a-3\right)^2\)
d) \(25x^2-20xy+4y^2\)
\(=\left(5x\right)^2-2.5x.2y+\left(2y\right)^2\)
\(=\left(5x-2y\right)^2\)
\(4x^2+4x+1\)
\(=\left(2x\right)^2+2.2x.1+1\)
\(=\left(2x+1\right)^2\)
\(1+12x+36x^2\)
\(=1+2.6x+\left(6x\right)^2\)
\(=\left(1+6x\right)^2\)
Đã trả lời: Câu hỏi của Naryu Wikashi - Toán lớp 8 | Học trực tuyến
a. x2 - 6x + 9
= x2 - 2x3 + 32
= (x - 3)2
b. x2 + x + \(\frac{1}{4}\)
= x2 + 2x\(\frac{1}{2}\)+ \(\left(\frac{1}{2}\right)^2\)
= (x + \(\frac{1}{2}\))2
c. 4x2 - \(\frac{1}{16}\)
= (2x)2 - \(\left(\frac{1}{4}\right)^2\)
= (2x +\(\frac{1}{4}\))(2x - \(\frac{1}{4}\))
d. (a + b)2 - 4
= (a + b)2 - 22
= (a + b + 2)(a + b - 2)
e. (a2 + 9)2 - 36a2
= (a2 + 9)2 - (6a)2
= (a2 + 9 + 6a)(a2 + 9 - 6a)
a. x2 + 6x + 9 = (x + 3)2
b. 25 + 10x + x2 = (5 + x)2
c. x2 + 8x + 16 = (x + 4)2
d. x2 + 14x + 49 = (x + 7)2
e. 4x2 + 12x + 9 = (2x + 3)2
f. 9x2 + 12x + 4 = (3x + 2)2
h. 16x2 + 8 + 1 = (4x + 1)2
i. 4x2 + 12xy + 9y2 = (2x + 3y)2
k. 25x2 + 20xy + 4y2 = (5x + 2y)2
a) \(=\left(x+3\right)^2\)
b) \(=\left(x+5\right)^2\)
c) \(=\left(x+4\right)^2\)
d) \(=\left(x+7\right)^2\)
e) \(=\left(2x+3\right)^2\)
f) \(=\left(3x+2\right)^2\)
h) \(=\left(4x+1\right)^2\)
i) \(=\left(2x+3y\right)^2\)
k) \(=\left(5x+2y\right)^2\)
a2 - 6a + 9 = (a-3)2
--
1-4x+4x2 = (1-2x)2
--
(a+b)2 - 1 = (a+b-1)(a+b+1)
--
4x2- 9 = (2x-3)(2x+3)
--
25x2 - 20xy + 4y2 = (5x - 2y)2
\(4x^2-9=\left(2x\right)^2-3^2=\left(2x-3\right)\times\left(2x+3\right)\)