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A=x14+x7+1
=(x14+x13+x12)-(x13+x12+x11)+(x11+x10+x9)-(x10+x9+x8)+(x8+x7+x6)-(x6+x5+x4)+(x5+x4+x3)-(x3+x2+x)+(x2+x+1)
Đặt B=x2+x+1
=>A=x12B-x11B+x9B-x8B+x6B-x4B+x3B-xB+B
=>A=B(x12-x11+x9-x8+x6-x4+x3-x+1)
Thay B=x2+x+1 vào A là xong
x^2 - 10x - 16
= x^2 - 2.x.5 + 25 - 25 - 1 6
= ( x - 5)^2 - 41
=( x - 5 )^2 - \(\left(\sqrt{41}\right)^2\)
= ( x - 5 - căn 41 ) ( x - 5 + căn 41)
thang Tran làm thế hơi rảnh
của mjk
x2-10x-16
=x2-2x-8x-16
=x(x-2)-8(x-2)
=(x-2)(x-8)
\(=x^2-\left(y-4\right)^2\)
\(=\left(x-y+4\right)\left(x+y-4\right)\)
\(=x^2-\left(y^2-8y+16\right)=x^2-\left(y-4\right)^2=\left(x-y+4\right)\left(x+y-4\right)\)
\(x^2-16+2\left(x+4\right)\)
\(=\left(x+4\right)\left(x-4\right)+2\left(x+4\right)\)
\(=\left(x+4\right)\left(x-4+2\right)\)
\(=\left(x+4\right)\left(x-2\right)\)
\(x^2-x-1=x^2-x+\frac{1}{4}-\frac{5}{4}=\left(x-\frac{1}{2}\right)^2-\left(\frac{\sqrt{5}}{2}\right)^2=\left(x-\frac{1-\sqrt{5}}{2}\right)\left(x-\frac{1+\sqrt{5}}{2}\right)\)
\(=\left(\sqrt{x}+1\right)\left(x-\sqrt{x}+1\right)\)
a,3x-6\(\sqrt{x}\)-6
=2(x-3\(\sqrt{x}\)-3)
=2(x-2\(\sqrt{x}\).\(\frac{3}{2}\)+\(\frac{9}{4}\)-\(\frac{21}{4}\))
=2[(x-\(\frac{3}{2}\))2-\(\frac{21}{4}\)]
2(x-\(\frac{3+\sqrt{21}}{2}\))(x-\(\frac{3-\sqrt{21}}{2}\))
b,x+4\(\sqrt{x}\)+3
=x+3\(\sqrt{x}\)+\(\sqrt{x}\)+3
=\(\sqrt{x}\)(\(\sqrt{x}\)+3) +(\(\sqrt{x}\)+3)
=(\(\sqrt{x}\)+1)(\(\sqrt{x}\)+3)
c,x-5\(\sqrt{x}\)-6
=x-6\(\sqrt{x}\)+\(\sqrt{x}\)-6
=\(\sqrt{x}\)(\(\sqrt{x}\)-6)+(\(\sqrt{x}\)-6)
=(\(\sqrt{x}\)+1)(\(\sqrt{x}\)-6)
d,x+5\(\sqrt{x}\)-14
=x+7\(\sqrt{x}\)-2\(\sqrt{x}\)-14
=\(\sqrt{x}\)(\(\sqrt{x}\)+7)-2(\(\sqrt{x}\)+7)
=(\(\sqrt{x}\)-2)(\(\sqrt{x}\)+7)
59 : 5 = ?