tính (x+2)^5 ; (2x-1)^4
( làm chi tiết giúp mình)
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\(a)\)
\(\left(x+y+z+t\right)\left(x+y-z-t\right)\)
\(=[\left(x+y\right)+\left(z+t\right)][\left(x+y\right)-\left(z-t\right)]\)
\(=\left(x+y\right)^2-\left(z+t\right)^2\)
\(=x^2+2xy+y^2-z^2-2zt-t^2\)
\(\left(x+2y+3z+t\right)^3\)
\(=\left(x+2y+3z+t\right)\left(x+2y+3z+t\right)\left(x+2y+3z+t\right)\)
\(=\left(4xy+6xz+2xt+x^2+4y^2+12yz+9z^2+4yt+6zt+t^2\right)\left(x+2y+3z+t\right)\)
\(=8y^3+12xy^2+36y^2z+12y^2t+6x^2y+54yz^2+36xyz+6yt^2+12xyt+36yzt+x^3+27z^3+27xz^2+9x^2z+t^3+3xt^2+9zt^2+3x^2t+18xzt+27z^2t\)
\(b)\)
\(\left(x-y+z-t\right)\left(x-y-z+t\right)\)
\(=\left(x-y\right)^2-\left(z+t\right)^2\)
\(=-z^2+2tz+y^2-2xy+x^2-t^2\)
\(\left(x^2-2x-1\right)^2\)
\(=\left(x^2+2x\right)^2-2\left(x^2+2x\right)+1\)
\(=x^4+4x^3-2x^2+4x^2+4x+1\)
\(=x^4+4x^3+2x^2+4x+1\)
a) -4x^2 + 9y^2
= 9y^2 - 4x^2
= (3y)^2 - (2x)^2
= ( 3y - 2x )(3y + 2x)
b) ( x + 1 )^3 - ( 2-x)^3
= ( x + 1 - 2 + x )[ (x + 1)^2 + (x + 1)(2 - x) + (2 - x)^2 ]
= (2x - 1) ( x^2 - x + 7)
c) 8 + ( 4x - 3 )^3
= 2^3 + ( 4x - 3)^3
= ( 2 + 4x - 3)( 4 - 8x + 6 + 16x^2 - 24x + 9)
= ( 4x - 1)( 16x^2 - 32x + 19)
d) 81 - (9 - x^2 )^2
= 9^2 - (9 - x^2)^2
= ( 9 - 9 + x^2)( 9 + 9 - x^2)
= x^2( 18 - x^2)
học tốt, mk ko tự tin với kết quả này lắm
a) \(x^2-2=\left(x-\sqrt{2}\right)\left(x+\sqrt{2}\right)\)
b) \(y^2-13=\left(y-\sqrt{13}\right)\left(y+\sqrt{13}\right)\)
c) \(2x^2-4=2\left(x^2-2\right)=2\left(x-\sqrt{2}\right)\left(x+\sqrt{2}\right)\)
d) \(\left(x^2-1\right)^2-\left(y+3\right)^2=\left(x^2-1-y-3\right)\left(x^2-1+y+3\right)\)
\(=\left(x^2-y-4\right)\left(x^2+y+2\right)\)
e) \(\left(a^2-b^2\right)^2-\left(a^2+b^2\right)^2=\left(a-b-a-b\right)\left(a-b+a+b\right)\)
\(-2a\left(a+2b\right)\)
f) \(a^6-b^6=\left(a^2\right)^3-\left(b^2\right)^3=\left(a^2-b^2\right)\left(a^4+a^2b^2+b^4\right)\)
\(=\left(a-b\right)\left(a+b\right)\left(a^4+a^2b^2+b^4\right)\)
(x+1)(x+2)(x+3)(x+4)-24
= (x^2 + 5x + 4)(x^2 + 5x + 6) - 24
đặt x^2 + 5x + 5 = a
ta có : (a - 1)(a + 1) - 24 = a^2 - 1 - 24
= a^2 - 25
= (a - 5)(a+5)
= (x^2 + 5x + 5 - 5)(x^2 + 5x + 5 + 5)
= (x^2 + 5x)(x^2 + 5x + 10)
= x(x + 5)(x^2 + 5x + 10)
x(x+1)(x+2)(x+3)+1
= (x^2 + 3x)(x^2 + 3x + 2) + 1
đặt x^2 + 3x + 1 = a
ta có : (a - 1)(a+1) + 1 = a^2 - 1 + 1 = a^2
= (x^2 + 3x + 1)^2
(x+1)(x+2)(x+3)(x+4)−24f,(x+1)(x+2)(x+3)(x+4)−24
=(x+1)(x+4)(x+2)(x+3)−24=(x+1)(x+4)(x+2)(x+3)−24
=(x2+5x+4)(x2+5x+6)−24=(x2+5x+4)(x2+5x+6)−24
Đặt t=x2+5x+4t=x2+5x+4 , ta có
t(t+2)−24t(t+2)−24
=t2+2t−24=t2+2t−24
=(t2+2t+1)−25=(t2+2t+1)−25
=(t+1)2−52=(t+1)2−52
=(t+1−5)(t+1+5)=(t+1−5)(t+1+5)
=(t−4)(t+6)=(t−4)(t+6)
=(x2+5x+4−4)(x2+5x+4+6)=(x2+5x+4−4)(x2+5x+4+6)
=(x2+5x)(x2+5x+10)
x(x+1)(x+2)(x+3)+1x(x+1)(x+2)(x+3)+1
=[x(x+3)][(x+1)(x+2)]+1=[x(x+3)][(x+1)(x+2)]+1
=(x2+3x)(x2+2x+x+2)+1=(x2+3x)(x2+2x+x+2)+1
=(x2+3x)(x2+3x+2)+1=(x2+3x)(x2+3x+2)+1(1)
Đặt x2+3x=t⇒x2+3x+2=t+2x2+3x=t⇒x2+3x+2=t+2
Do đó (1)=t(t+2)+1=t2+2t+1=(t+1)2(1)=t(t+2)+1=t2+2t+1=(t+1)2(*)
Vì t=x2+3xt=x2+3x nên
(*)=(x2+3x+1)2
(2x4-8x2+8) : (4-2x2)
= 2(x4-4x2+4) : 2(2-x2)
= (x4-4x2+4) : (2-x2)
= (x2 - 2) : (2-x2)
= - 1
\(2x^4+8x^2+8=2\left(x^4+4x^2+4\right)=2\left(x^2+2\right)^2\)
\(\left(4-2x^2\right)=2\left(2-x^2\right)\Rightarrow\frac{2x^4+8x^2+8}{4-2x^2}=\frac{2\left(x^2+2\right)^2}{2\left(2-x^2\right)}=\frac{\left(x^2+2\right)^2}{2-x^2}\)
Nếu không sai đề thì tự phân tích rồi thực hiện phép chia đa thức
a^2-2ab+1+2b-2a-3b^2 = a^2 -2a . b+1 +2b-2a-3b^2 = -(b+a-1)(3b-a+1)
nha bạn chúc bạn học tốt
cảm ơn bạn ♡•꧁༺༒✰ŞŦΔŘ✰༒༺꧁•♡✿(➻❥𝒢𝑜𝓁𝒹❃𝒮𝓉𝒶𝓇✤) ❀ nha
a, x^3 + y^3 = (x + y)(x^2 - xy + y^2) = (x + y)[(x+y)^2 - 3xy]
mà x + y = 1 và xy = -1
=> x^3 + y^3 = 1(1^2 - 3(-1)) = 4
b, x^3 - y^3 = (x - y)(x^2 + xy + y^2) = (x-y)[(x-y)^2+3xy]
có x - y = 1 và xy = 6
=> 1(1^2 + 3.6) = 19
( x+2)^5 : (2x-1)^4
(x+2)(x+2)(x+2)(x+2)(x+2) : (2x-1)(2x-1)(2x-1)(2x-1)
( x+2)( 1+1+1+1+1) : (2x-1)(1+1+1+1)
(x+2) . 5 : (2x-1) . 4
(x+2) . 5 : 2(x+2) -5 . 4
đề ghi thế làm sao giải