25a2+4b2-20ab = ?
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1: 2a+2b=2(a+b)
2: 2a+4b+6c
=2*a+2*2b+2*3c
=2(a+2b+3c)
3: \(-7a-14ab-21b=-7\left(a+2ab+3b\right)\)
4: \(2ax-2ay+2a=2a\left(x-y+1\right)\)
5: \(=3a\cdot ax-3a\cdot2ay+3a\cdot4=3a\left(ax-2ay+4\right)\)
6: \(=2\cdot2ax-2\cdot ay-2\cdot1=2\cdot\left(2ax-ay-1\right)\)
7: =a^2-(2b)^2
=(a-2b)(a+2b)
8: =(5a)^2-1^2
=(5a-1)(5a+1)
9: =9(16a^2-9)
=9(4a-3)(4a+3)
\(=25a^2-\left(5x-1\right)^2=\left(5a+5x-1\right)\left(5a-5x+1\right)\)
\(25a^2-25x^2+10x-1\)
\(=25a^2-\left(5x-1\right)^2\)
\(=\left(5a-5x+1\right)\left(5a+5x-1\right)\)
√25a2 + 3a = 5|a| + 3a = 5a + 3a = 8a
(do a ≥ 0 nên |a| = a)
\(25a^2-20ab+4b^2\)
= \(\left(5a\right)^2\) \(-2.5a.2b\) \(+\left(2b\right)^2\)
= \(\left(5a-2b\right)^2\)
\(=\left(5a\right)^2-2\cdot5\cdot2\cdot a\cdot b+\left(2b\right)^2=\left(5a-2b\right)^2\)
A=9x^2−6x+1
=(3x)^2−2.3x.1+1^2
=(3x−1)^2
B=(2x+3y)^2+(2x+3y)+1(2x+3y)2+(2x+3y)+1
=[(2x+3y)^2+2.(2x+3y).1/2+(1/2)^2]+3/4
=(2x+3y+1/2)^2+3/4
=(2x+3y+1)(2x+3y)+1
a) \(25a^2-b^2=\left(5a-b\right)\left(5a+b\right)\)
b) \(z^2+z-mz-m=z\left(z+1\right)-m\left(z+1\right)=\left(z+1\right)\left(z-m\right)\)
a , 25a2 - b2
= (5a -b ) ( 5a+ b )
b , z2 + z - m z -m
= z ( z + 1) - m( z + 1 )
= ( z + 1 ) ( z - m )
1: \(a^2-4b^2-2a-4b\)
\(=\left(a-2b\right)\left(a+2b\right)-2\left(a+2b\right)\)
\(=\left(a+2b\right)\left(a-2b-2\right)\)
2: \(x^3+2x^2-2x-1\)
\(=\left(x-1\right)\left(x^2+x+1\right)+2x\left(x-1\right)\)
\(=\left(x-1\right)\left(x^2+3x+1\right)\)
25a2+4b2-20ab = (5a)2 - 2.5.2ab + (2b)2 = (5a - 2b)2