Violympic toán 7
Các câu hỏi tương tự
Tìm x, biết:
a) 4left|3x-1right|+left|xright|-2left|x-5right|+7left|x-3right|12
b) 3left|x+4right|-left|2x+1right|-5left|x+3right|+left|x+9right|5
c)
left|2frac{1}{5}-xright|+left|x-frac{1}{5}right|+8frac{1}{5}1,2
d) 2left|x+3frac{1}{2}right|+left|xright|-3frac{1}{2}left|2frac{1}{5}-xright|
Đọc tiếp
Tìm \(x,\) biết:
a) \(4\left|3x-1\right|+\left|x\right|-2\left|x-5\right|+7\left|x-3\right|=12\)
b) \(3\left|x+4\right|-\left|2x+1\right|-5\left|x+3\right|+\left|x+9\right|=5\)
c) \( \left|2\frac{1}{5}-x\right|+\left|x-\frac{1}{5}\right|+8\frac{1}{5}=1,2\)
d) \(2\left|x+3\frac{1}{2}\right|+\left|x\right|-3\frac{1}{2}=\left|2\frac{1}{5}-x\right|\)
Bài 1: Thu gọn
a) frac{1}{5}x^4y^3-3x^4y^3
b) 5x^2y^5-frac{1}{4}x^2y^5
c) frac{1}{7}x^2y^3.left(-frac{14}{3}xy^2right)-frac{1}{2}xy.left(x^2y^{text{4}}right)
d) left(3xyright)^2.left(-frac{1}{2}x^3y^2right)
e) -frac{1}{4}xy^2+frac{2}{5}x^2y+frac{1}{2}xy^2-x^2y
f) frac{1}{2}x^4y.left(-frac{2}{3}x^3y^2right)-frac{1}{3}x^7y^3
g) frac{1}{2}x^2y.left(-10x^3yz^2right).frac{1}{4}x^5y^3z
h) 4.left(-frac{1}{2}xright)^2-frac{3}{2}x.left(-xright)+frac{1}{3}x^2
i) 1frac{2}{3}x^3y.left(frac{-1}{2}xy...
Đọc tiếp
Bài 1: Thu gọn
a) \(\frac{1}{5}x^4y^3-3x^4y^3\)
b) \(5x^2y^5-\frac{1}{4}x^2y^5\)
c) \(\frac{1}{7}x^2y^3.\left(-\frac{14}{3}xy^2\right)-\frac{1}{2}xy.\left(x^2y^{\text{4}}\right)\)
d) \(\left(3xy\right)^2.\left(-\frac{1}{2}x^3y^2\right)\)
e) \(-\frac{1}{4}xy^2+\frac{2}{5}x^2y+\frac{1}{2}xy^2-x^2y\)
f) \(\frac{1}{2}x^4y.\left(-\frac{2}{3}x^3y^2\right)-\frac{1}{3}x^7y^3\)
g) \(\frac{1}{2}x^2y.\left(-10x^3yz^2\right).\frac{1}{4}x^5y^3z\)
h) \(4.\left(-\frac{1}{2}x\right)^2-\frac{3}{2}x.\left(-x\right)+\frac{1}{3}x^2\)
i) \(1\frac{2}{3}x^3y.\left(\frac{-1}{2}xy^2\right)^2-\frac{5}{4}.\frac{8}{15}x^3y.\left(-\frac{1}{2}xy^2\right)^2\)
k) \(-\frac{3}{2}xy^2.\left(\frac{3}{4}x^2y\right)^2-\frac{3}{5}xy.\left(-\frac{1}{3}x^4y^3\right)+\left(-x^2y\right)^2.\left(xy\right)^2\)
n) \(-2\frac{1}{5}xy.\left(-5x\right)^2+\frac{3}{4}y.\frac{2}{3}\left(-x^3\right)-\frac{1}{9}.\left(-x\right)^3.\frac{1}{3}y\)
m) \(\left(-\frac{1}{3}xy^2\right)^2.\left(3x^2y\right)^3.\left(-\frac{5}{2}xy^2z^3\right)^{^2}\)
p) \(-2y.\left|2\right|x^4y^5.\left|-\frac{3}{4}\right|x^3y^2z\)
13 tháng 9 2019 lúc 21:45
Bài 1: Tìm x biết: \(\left|x-3\right|+\left|x+2\right|=7\)
Bài 2: CMR: \(\frac{1}{4}+\frac{1}{4^2}+\frac{1}{4^3}+...+\frac{1}{4^{999}}+\frac{1}{4^{1000}}< \frac{1}{3}\)
Bài 3: Tìm x biết:
a) \(x\left(x-2\right)\left(x-3\right)>0\)
b) \(x\left(x-2\right)\left(x-3\right)< 0\)
tìm x biết
a.\(\frac{-3}{4}-\left|\frac{4}{5}-x\right|=-1\)
b.\(\left|\frac{-1}{2}-x\right|=\frac{1}{3}\)
c.\(\left|2^1_2+x\right|-\frac{-2}{3}=3\)
d.\(\frac{-5}{7}-\left|\frac{1}{2}-x\right|=\frac{-11}{4}\)
e.\(\left|3x+4\right|=2\left|2x-9\right|\)
Bài 1: Tìm x biết:
a, \(x.\cdot\left(\frac{1}{4}+\frac{1}{5}\right)-\left(\frac{1}{7}+\frac{1}{8}\right)=0\)
b, \(\left(5x-1\right).\left(2x-\frac{1}{3}\right)=0\)
c, \(\frac{3x+2}{5x+7}=\frac{3x-1}{5x+1}\)
d, \(\frac{x+1}{2x+1}=\frac{0,5x+2}{x+3}\)
e, \(\frac{-3}{4}-\left|\frac{4}{5}-x\right|=-1\)
bài 1 tính
Afrac{a+b}{b+c} biết frac{b}{a}2;frac{c}{b}3
bài 2 tìm x
a) frac{72-x}{7}frac{x-40}{9}
b) frac{x+4}{20}frac{5}{x+4}
bài 3 tìm x,y
frac{1+2y}{18}frac{1+4y}{24}frac{1+6y}{6x}
bài 8 tìm x,y,z
a) x:y:z3:4:5 và 2x2+2y2-3z2-100
b)frac{x}{y+z+1}frac{y}{x+z+1}frac{z}{x+y-2}x+y+z
c) left|x-3right|+left|y+5right|+left|x+y+zright|0
d) left|2x-5right|+left|2y-zright|+left|4z-2right|0
Đọc tiếp
bài 1 tính
\(A=\frac{a+b}{b+c}\) biết \(\frac{b}{a}=2;\frac{c}{b}=3\)
bài 2 tìm x
a) \(\frac{72-x}{7}=\frac{x-40}{9}\)
b) \(\frac{x+4}{20}=\frac{5}{x+4}\)
bài 3 tìm x,y
\(\frac{1+2y}{18}=\frac{1+4y}{24}=\frac{1+6y}{6x}\)
bài 8 tìm x,y,z
a) x:y:z=3:4:5 và 2x2+2y2-3z2=-100
b)\(\frac{x}{y+z+1}=\frac{y}{x+z+1}=\frac{z}{x+y-2}=x+y+z\)
c) \(\left|x-3\right|+\left|y+5\right|+\left|x+y+z\right|=0\)
d) \(\left|2x-5\right|+\left|2y-z\right|+\left|4z-2\right|=0\)
1.tìm x
a.frac{-5}{8}+xfrac{4}{9}
b.1^3_4.x+1^1_2-frac{4}{5}
c.frac{1}{4}+frac{3}{4}xfrac{3}{4}
d.x.left(frac{1}{4}+frac{1}{5}right)-left(frac{1}{7}+frac{1}{8}right)0
e.frac{3}{35}-left(frac{3}{5}+xright)frac{2}{7}
f.frac{3}{7}+frac{1}{7}:xfrac{3}{14}
g.left(5x-1right)left(2x-frac{1}{3}right)0
Đọc tiếp
1.tìm x
a.\(\frac{-5}{8}+x=\frac{4}{9}\)
b.\(1^3_4.x+1^1_2=-\frac{4}{5}\)
c.\(\frac{1}{4}+\frac{3}{4}x=\frac{3}{4}\)
d.\(x.\left(\frac{1}{4}+\frac{1}{5}\right)-\left(\frac{1}{7}+\frac{1}{8}\right)=0\)
e.\(\frac{3}{35}-\left(\frac{3}{5}+x\right)=\frac{2}{7}\)
f.\(\frac{3}{7}+\frac{1}{7}:x=\frac{3}{14}\)
g.\(\left(5x-1\right)\left(2x-\frac{1}{3}\right)=0\)
3/a)Mleft(xright)frac{1}{2}x^2-3x-x^3+3
-x^3+frac{1}{2}x^2-3x+3
Nleft(xright)-4x+x^2+frac{1}{2}x^3+6
frac{1}{2}x^3+x^2-4x^3+6
b)Ta có:text{A}left(xright)Mleft(xright)-Nleft(xright)
hay text{A}left(xright)left(-x^3+frac{1}{2}x^2-3x+3right)-left(frac{1}{2}x^3+x^2-4x+6right)
-x^3+frac{1}{2}x^2-3x+3-frac{1}{2}x^3-x^2+4x-6
-frac{3}{2}x^3-frac{1}{2}x^2+x-3
Đặttext{A}left(xright)0
Rightarrow-frac{3}{2}x^3-frac{1}{2}x^2+x-30
-frac{3}{2}...
Đọc tiếp
3/a)\(M\left(x\right)=\frac{1}{2}x^2-3x-x^3+3\)
\(=-x^3+\frac{1}{2}x^2-3x+3\)
\(N\left(x\right)=-4x+x^2+\frac{1}{2}x^3+6\)
\(=\frac{1}{2}x^3+x^2-4x^3+6\)
b)Ta có:\(\text{A}\left(x\right)=M\left(x\right)-N\left(x\right)\)
hay \(\text{A}\left(x\right)=\left(-x^3+\frac{1}{2}x^2-3x+3\right)-\left(\frac{1}{2}x^3+x^2-4x+6\right)\)
\(=-x^3+\frac{1}{2}x^2-3x+3-\frac{1}{2}x^3-x^2+4x-6\)
\(=-\frac{3}{2}x^3-\frac{1}{2}x^2+x-3\)
Đặt\(\text{A}\left(x\right)=0\)
\(\Rightarrow-\frac{3}{2}x^3-\frac{1}{2}x^2+x-3=0\)
\(-\frac{3}{2}x^3-\frac{1}{2}x^2=-x+3\)
\(-2\left(x^3-x^2\right)=-x+3\)
\(x^3-x^2+x=3+2=5\)
\(x^2=5\)
\(\Rightarrow x=\sqrt{5}\)
Vậy \(\text{A}\left(x\right)\) có 1 nghiệm là \(\sqrt{5}\)
tìm x biết
a) \(\frac{x-1}{x+2}=\frac{4}{5}\left(x\ne-2\right)\) b)22x+1+4x+3=264 c)\(\frac{x^2}{-8}=\frac{27}{x}\left(x\ne0\right)\) d)\(\frac{x+7}{-20}=\frac{-5}{x+7}\left(x\ne-7\right)\) e)\(\frac{x}{-8}=\frac{2}{-x^3}\left(x\ne0\right)\)