PTĐTTNT : n^2 + 10
`n) 81x^2 - 6yz - 9y^2 - z^2`
ptđttnt
\(=81x^2-\left(z+3y\right)^2\)
\(=\left(9x+z+3y\right)\left(9x-z-3y\right)\)
PTĐTTNT :
x^2-(m+n)x+mn
\(=x^2-xm-xn+mn=x\left(x-m\right)-n\left(x-m\right)=\left(x-n\right)\left(x-m\right)\)
PTĐTTNT
a) x3 - 3x2 + 1 - 3x
b) 3x2 - 7x - 10
a) \(x^3-3x^2+1-3x=\left(x^3+1\right)-\left(3x^2+3x\right)\)
\(=\left(x+1\right)\left(x^2-x+1\right)-3x\left(x+1\right)\)
\(=\left(x+1\right)\left(x^2-x+1-3x\right)\)
\(=\left(x+1\right)\left(x^2-4x+1\right)\)
b) \(3x^2-7x-10=3x^2+3x-10x-10\)
\(=3x\left(x+1\right)-10\left(x+1\right)\)
\(=\left(x+1\right)\left(3x-10\right)\)
a) \(x^3-3x^2-3x+1=\left(x^3+1\right)-\left(3x^2+3x\right)\)
= \(\left(x+1\right)\left(x^2-x+1\right)-3x\left(x+1\right)\)
= \(\left(x+1\right)\left(x^2-x+1-3x\right)\)
= \(\left(x+1\right)\left(x^2-4x+1\right)\)
b) \(3x^2-7x-10=\left(3x^2+3x\right)-\left(10x+10\right)\)
= \(3x\left(x+1\right)-10\left(x+1\right)\)
= \(\left(x+1\right)\left(3x-10\right)\)
ptđttnt:
x10+x5+1
x^10 + x^5 + 1
= x^10 + x^9 - x^9 + x^8 - x^8 + x^7 - x^7 + x^6 - x^6 + x^5 + x^5 - x^5 + x^4 - x^4 + x^3 - x^3 + x^2 - x^2 + x - x + 1
= (x^10 + x^9 + x^8) - (x^9 + x^8 + x^7) + (x^7 + x^6 + x^5) - (x^6 + x^5 + x^4) + (x^5 + x^4 + x^3) - (x^3 + x^2 + x) + (x^2 + x + 1)
= x^8 (x^2 + x + 1) - x^7 (x^2 + x + 1) + x^5 (x^2 + x + 1) - x^4 (x^2 + x + 1) + x^3 (x^2 + x + 1) - x (x^2 + x + 1) + (x^2 + x + 1)
= (x^2 + x + 1) (x^8 - x^7 + x^5 - x^4 + x^3 - x + 1)
PTĐTTNT bằng 3 cách
a)x^2+7x+12
b)3x^2-5x+2
c)x^2+9x-10
d)x^2-7x-8
e)2x^2+3x-5
a) \(x^2+7x+12\)
\(=x^2+3x+4x+12\)
\(=x\left(x+3\right)+4\left(x+3\right)\)
\(=\left(x+3\right)\left(x+4\right)\)
b) \(3x^2-5x+2\)
\(=3x^2-3x-2x+2\)
\(=3x\left(x-1\right)-2\left(x-1\right)\)
\(=\left(x-1\right)\left(3x-2\right)\)
a) x2 + 7x + 12 = x2 + 3x + 4x + 12 = x(x + 3) + 4(x + 3) = (x + 4)(x + 3)
b) 3x2 - 5x + 2 = 3x2 - 3x - 2x + 2 = 3x(x - 1) - 2(x - 1) = (3x - 2)(x - 1)
c) x2 + 9x - 10 = x2 + 10x - x - 10 = x(x + 10) - (x + 10) = (x - 1)(x + 10)
d) x2 - 7x - 8 = x2 - 8x + x - 8 = x(x - 8) + (x - 8) = (x + 1)(x - 8)
e) 2x2 + 3x - 5 = 2x2 + 5x - 2x - 5 = x(2x + 5) - (2x + 5) = (x - 1)(2x + 5)
PTĐTTNT : ( 1 + a + a^2 + ........ + a^n-1 ) . (1 + a + a^2 +........ +a^n+1 )
ai giải giúp mình với, đang cần gấp giải đc tặng 4 like
PTĐTTNT:
xn + xn+3 -xn
\(x^n+x^{n+3}-x^n=x^{n+3}=x^n\cdot x^3\)
PTĐTTNT :
`4x^2-4x-25y^2+1`
\(\left(2x-1\right)^2-25y^2=\left(2x-1-5y\right)\left(2x-1+5y\right)\)
PTĐTTNT`3x-3y+2x^2-2y^2`
\(=3\left(x-y\right)+2\left(x-y\right)\left(x+y\right)=\left(x-y\right)\left(3+2x+2y\right)\)