tim x
4^2.x + 3^2.x -|-2^5.10| : 16 = 55
Cau 1:
Tim x, biet: 1-4+7-10+.............-x=-75
Cau 2:
Cho x1, x2, x3, x4, x5 thuộc Z
Biết x1+ x2 + x3 + x4 + x5=0
và x1 + x2=x3+ x4= x4 + x5 =2
Tinh x3, x4 , x5
Cau 3: Tim x biet
(x+7+1) chia het cho (x+7)
tim X:
X x 2 + X x 3 + X x4 +X=2130
Xx2+Xx3+Xx4+X=2130
Xx2+Xx3+Xx4+Xx1=2130
Xx(2+3+4+1) =2130
Xx10 =2130
X =2130:10
X =213
tk mk nha ^_^
Xx2 +Xx3+Xx4+Xx1=2130
Xx(2+3+4+1)=2130
Xx10=2130
x=2130:10
X=213
Xx(1+2+3+4)=2130
Xx10=2130
X=2130:10
X=213
Vậy X=213
tim du cua
a)x^3-9x^2+6x+16 : x-3
b)x+x^3+x^9+x^27:x-1 ; :x^2-1
c)x^99+x^55+x^11+x+7 :x+1 ; :x^2+1
d)f(x)=x^50+x^49+...+x^2+x+1 :x^2-1
A=(x-2)(x4+2x3+4x2+8x+16)với x=3
Ta có: \(A=\left(x-2\right)\left(x^4+2x^3+4x^2+8x+16\right)\)
\(=x^4+2x^3+4x^2+8x+16\)
\(=3^4+2\cdot3^3+4\cdot3^2+8\cdot3+16\)
\(=81+54+36+24+16\)
\(=211\)
tim x : 1+2+3+...+x=55
Dãy trên có số các số hạng là:
(x-1):1+1 = x (số)
=> (x+1).x:2 = 55
x.(x+1) = 55.2
x.(x+1) = 110
Mà 10.11 = 110 => x = 10
1+2+3+.....+x = 55
=> x(x+1) = 55 x 2 = 110 = 10 x (10 + 1)
Vậy x = 10
BT2: Thực Hiện các phép tính , sau đó tính giá trị biểu thức
a) A=(x-2).(x4+2x3+4x2+8x+16) Với x=3 ĐS A=211
b) B=(x+1).(x7-x6+x5-x4+x3-x2+x-1) Với x=2 ĐS B=255
a: A=x^5-32
Khi x=3 thì A=3^5-32=243-32=211
b: B=x^8-x^7+x^6-x^5+x^4-x^3+x^2-x+x^7-x^6+x^5-x^4+x^3-x^2+x-1
=x^8-1
=2^8-1=255
tim x,biet: 1+2+3+5+...+x=55
1+2+3+...+x=55
Tim so x
1) (x2-4x+16) (x+4)-x(x+1) (x+2)+3x2=0
2) (8x+2) (1-3x)+(6x-1) (4x-10)=-50
3) (x2+2x+4) (2-x)+x(x-3) (x+4)-x2+24=0
4) (\(\dfrac{x}{2}\)x2+3) (5-6x)+(12x-2) (\(\dfrac{x}{4}\)x4+3)=0
1)(x2-4x+16)(x+4)-x(x+1)(x+2)+3x2=0
\(\Rightarrow\)(x3+64)-x(x2+2x+x+2)+3x2=0
\(\Rightarrow\)x3+64-x3-2x2-x2-2x+3x2=0
\(\Rightarrow\)-2x+64=0
\(\Rightarrow\)-2x=-64
\(\Rightarrow\)x=\(\dfrac{-64}{-2}\)
\(\Rightarrow x=32\)
2)(8x+2)(1-3x)+(6x-1)(4x-10)=-50
\(\Rightarrow\)8x-24x2+2-6x+24x2-60x-4x+10=50
\(\Rightarrow\)-62x+12=50
\(\Rightarrow\)-62x=50-12
\(\Rightarrow\)-62x=38
\(\Rightarrow\)x=\(-\dfrac{38}{62}=-\dfrac{19}{31}\)
3)(x2+2x+4)(2-x)+x(x-3)(x+4)-x2+24=0
\(\Rightarrow\)8-x3+x(x2+4x-3x-12)-x2+24=0
\(\Rightarrow\)8-x3+x3+4x2-3x2-12x-x2+21=0
\(\Rightarrow\)-12x+29=0
\(\Rightarrow\)-12x=-29
\(\Rightarrow\)x=\(\dfrac{-29}{-12}=\dfrac{29}{12}\)