Bai 1: Rut gon bieu thuc
a, ( m+n )2 - ( m-n )2 + ( m+n ) ( m-n)
b, ( a+b)3 + ( a-b )3 - 2a3
c, ( 2x+1)2 + 2(4x2 - 1) + ( 2x-1 )2
d, ( a+b+c )2 - 2(a+b+c) (b+c ) + ( b+c )2
Những câu hỏi liên quan
Rut gon bieu thuc:
a)(m+n)^2-(m-n)^2+(m+n)(m-n)
b)(a+b)^3+(a-b)^3-2a^3
c)(2x+1)^2+2(4x^2-1)+(2x-1)^2
d)(a+b+c)^2-2(a+b+c)(b+c)+(b+c)^2
B1: rut gon bieu thuc
a, (x+y)^2-4(x-y)^2
b, 2(x-y)(x+y)+(x+y)^2+(x-y)^2
B2: tim X
a, (2X-1)^2-4(X+2)^2=9
b, 3(X-1)^2-3X(X-5)=21
B3: Cho bieu thuc
M=(x+3)^3-(x-1)^3+12x(x-1)
a, Rut gon bieu thuc tren
b, Tinh gia tri M tai x=-2/3
c, Tim x de M=16
1)a)=>x2+y2+2xy-4(x2-y2-2xy)
=>x2+y2+2xy-4.x2+4y2+8xy
=>-3.x2+5y2+10xy
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bai 1. 11/3.40/13+37/5:7/33-(11/13.1/3+33/7:5/2)
bai 2.tim x
a,3.(x-1)-5.(-7)(-2)^3-2x
b,2./(1-x)^2+1/-2^2.38
bai 3,cho bieu thuc
Mn+1/n+1 - 3-8n/n+1 + 8/n+1
tim cac gia tri cua n de bieu thuc M co gia tri la so nguyen
bai 4,So hoc sinh cua 1 truong ko qua 1000 em,neuxeptoan bo so hoc sinh cua truong do thanh cac hang,moi hang 20 nguoi thi con thieu 5 nguoi,neu xep moi hang 25 nguoi hoac 30 nguoi thi deu thua 15 nguoi , neu xep 42 hang thi vua du . hoi truong do co bao nhieu hoc sinh...
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bai 1. 11/3.40/13+37/5:7/33-(11/13.1/3+33/7:5/2)
bai 2.tim x
a,3.(x-1)-5.(-7)=(-2)^3-2x
b,2./(1-x)^2+1/-2^2.3=8
bai 3,cho bieu thuc
M=n+1/n+1 - 3-8n/n+1 + 8/n+1
tim cac gia tri cua n de bieu thuc M co gia tri la so nguyen
bai 4,So hoc sinh cua 1 truong ko qua 1000 em,neuxeptoan bo so hoc sinh cua truong do thanh cac hang,moi hang 20 nguoi thi con thieu 5 nguoi,neu xep moi hang 25 nguoi hoac 30 nguoi thi deu thua 15 nguoi , neu xep 42 hang thi vua du . hoi truong do co bao nhieu hoc sinh
bai 5,cho bieu thuc
A=2+2^2+...+2^200
c/m rang
a, A+2 la 1 luy thua cua 2
b, Achia het cho 30
c,A co phai la so chinh phuong ko ? vi sao ?
bai 6,cho 2 bieu thuc
A=1/1+2 + 1/1+2+3 + ...1/1+2+3+...+99
B=1 + 1/2^2+1/3^2 + ...+1/49^2
c/m rang A<B
3(x-1)-5x(-7)=-2^3-2x
3x-3x1--35=-8-2x
3x+32=-8-2x
3x+2x=-8-32
5x=-40
x=-40:5
x=-8
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cho 2 bieu thuc A=x+x^2/2-x va B=2x/x+1+3/x-2-2x^2+1/x^2-x-2 a, tinh gia tri cua A khi /2x-3/=1 b,tim dieu kien xac dinh va rut gon bieu thuc B c,tim so nguyen x de P=A.B dat gia tri lon nhat
mk dang can gap
a:
ĐKXĐ: x<>2
|2x-3|=1
=>\(\left[{}\begin{matrix}2x-3=1\\2x-3=-1\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=2\left(loại\right)\\x=1\left(nhận\right)\end{matrix}\right.\)
Thay x=1 vào A, ta được:
\(A=\dfrac{1+1^2}{2-1}=\dfrac{2}{1}=2\)
b: ĐKXĐ: \(x\notin\left\{-1;2\right\}\)
\(B=\dfrac{2x}{x+1}+\dfrac{3}{x-2}-\dfrac{2x^2+1}{x^2-x-2}\)
\(=\dfrac{2x}{x+1}+\dfrac{3}{x-2}-\dfrac{2x^2+1}{\left(x-2\right)\left(x+1\right)}\)
\(=\dfrac{2x\left(x-2\right)+3\left(x+1\right)-2x^2-1}{\left(x+1\right)\left(x-2\right)}\)
\(=\dfrac{2x^2-4x+3x+3-2x^2-1}{\left(x+1\right)\left(x-2\right)}\)
\(=\dfrac{-x+2}{\left(x+1\right)\left(x-2\right)}=-\dfrac{1}{x+1}\)
c: \(P=A\cdot B=\dfrac{-1}{x+1}\cdot\dfrac{x\left(x+1\right)}{2-x}=\dfrac{x}{x-2}\)
\(=\dfrac{x-2+2}{x-2}=1+\dfrac{2}{x-2}\)
Để P lớn nhất thì \(\dfrac{2}{x-2}\) max
=>x-2=1
=>x=3(nhận)
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1) rút gọn các đẳng thức sau
a) (m+n)^2-(m-n)^2+(m+n)(m-n)
b) (a+b)^2-(a-b)^2-2a^3
c) (2x+1)^2+(2x-1)^2+2(4x^2-1)
d) (a+b+c)^2-2(a+b+c)^2(b+c)=(b=+c)^2
a) \(\cdot\left(m+n\right)^2-\left(m-n\right)^2+\left(m+n\right)\left(m-n\right)\)
\(=\left(m+n+m-n\right)\left(m+n-m+n\right)+\left(m+n\right)\left(m-n\right)\)
\(=\left(2m\cdot2n\right)+m^2-n^2\)
\(=4mn+m^2-n^2\)
b) \(\left(a+b\right)^2-\left(a-b\right)^2-2a^3\)
\(=\left(a+b+a-b\right)\left(a+b-a+b\right)-2a^3\)
\(=2ab-2a^3\)
c) \(\left(2x+1\right)^2+\left(2x-1\right)^2+2\left(4x^2-1\right)\)
\(=\left(2x+1\right)^2+2\left(2x+1\right)\left(2x-1\right)+\left(2x-1\right)^2\)
\(=\left(2x+1+2x-1\right)^2\)
\(=\left(4x\right)^2=16x^2\)
d) \(\left(a+b+c\right)^2-2\left(a+b+c\right)\left(b+c\right)+\left(b+c\right)^2\)
\(=\left(a+b+c-b-c\right)^2=a^2\)
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xin lỗi mk ghi sai đề ở bài :d) (a+b+c)^2-2(a+b+c)(b+c)+(b+c)^2
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giai dum minh bai nay voi :c=x/2x-2+x^2+1/2-2x^2
a)tim x de a co nghia
b)rut gon bieu thuc c
c)tim gia tri cua x de bieu thuc kia =1/2
giúp mình cảm ơn nhìu nha !
cho a,b,c khac nhau doi mot va 1/a+1/b+1/c=0.rut gon cac bieu thuc
N=bc/a^2+2bc+CA/B^2+2AC+AB/C^2+2AB
cho \(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}=0\) va a,b,c khac 0. Rut gon bieu thuc N=\(\frac{1}{a^2+2ab}+\frac{1}{b^2+2ca}+\frac{1}{c^2+2ab}\)
bai 1. 11/3.40/13+37/5:7/33-(11/13.1/3+33/7:5/2)bai 2.tim xa,3.(x-1)-5.(-7)(-2)^3-2xb,2./(1-x)^2+1/-2^2.38bai 3,cho bieu thuc Mn+1/n+1 - 3-8n/n+1 + 8/n+1tim cac gia tri cua n de bieu thuc M co gia tri nguyenbai 4,So hoc sinh cua 1 truong ko qua 1000 em,neuxeptoan bo so hoc sinh cua truong do thanh cac hang,moi hang 20 nguoi thi con thieu 5 nguoi,neu xep moi hang 25 nguoi hoac 30 nguoi thi deu thua 15 nguoi , neu xep 42 hang thi vua du . hoi truong do co bao nhieu hoc sinh bai 5,cho bieu thuc A2+...
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bai 1. 11/3.40/13+37/5:7/33-(11/13.1/3+33/7:5/2)
bai 2.tim x
a,3.(x-1)-5.(-7)=(-2)^3-2x
b,2./(1-x)^2+1/-2^2.3=8
bai 3,cho bieu thuc
M=n+1/n+1 - 3-8n/n+1 + 8/n+1
tim cac gia tri cua n de bieu thuc M co gia tri nguyen
bai 4,So hoc sinh cua 1 truong ko qua 1000 em,neuxeptoan bo so hoc sinh cua truong do thanh cac hang,moi hang 20 nguoi thi con thieu 5 nguoi,neu xep moi hang 25 nguoi hoac 30 nguoi thi deu thua 15 nguoi , neu xep 42 hang thi vua du . hoi truong do co bao nhieu hoc sinh
bai 5,cho bieu thuc
A=2+2^2+...+2^200
c/m rang
a, A+2 la 1 luy thua cua 2
b, Achia het cho 30
c,A co phai la so chinh phuong ko ? vi sao ?
bai 6,cho 2 bieu thuc
A=1/1+2 + 1/1+2+3 + ...1/1+2+3+...+99
B=1 + 1/2^2+1/3^2 + ...+1/29^2
c/m rang A<B
ai co the giup bai nao thi noi luon cach giai nhe
le len may bn
toàn bọn gà ko biết cách làm
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