a)x=1;2;-2(bạn nên tự giải)
b)=>\(\dfrac{1\cdot2\cdot3\cdot4\cdot...\cdot30\cdot31}{4\cdot6\cdot8\cdot10\cdot...\cdot62\cdot64}\)=2x
=>\(\dfrac{2\cdot3\cdot4\cdot5\cdot...\cdot30\cdot31}{60\left(2\cdot3\cdot4\cdot5\cdot...\cdot30\cdot31\right)\cdot64}=2x\)
=>\(\dfrac{1}{60\cdot64}=2x\)=> 1/3840 =2x
=>x = 1/7680
c)=>4x - 2x = 6x - 3x
=>2x (2x-1)= 3x(2x-1)
=> 2x = 3x
=>x = 0
P = \(1+\dfrac{1}{2}\cdot\left(1+2\right)+\dfrac{1}{3}\cdot\left(1+2+3\right)+\dfrac{1}{4}\cdot\left(1+2+3+4\right)+...+\dfrac{1}{16}\cdot\left(1+2+3+...+16\right)\)
Cho a + b + c = 2016 và \(\dfrac{1}{a+b}+\dfrac{1}{b+c}+\dfrac{1}{c+a}=\dfrac{1}{3}.\) Tính S = \(\dfrac{a}{b+c}+\dfrac{b}{c+a}+\dfrac{c}{a+b}\)
Giải giúp mình nha.
\(C=25\cdot\left(-\dfrac{1}{3}\right)^3+\dfrac{1}{5}-2\cdot\left(-\dfrac{1}{2}\right)^2-\dfrac{1}{2}\)
\(F=\left(-\dfrac{3}{2}\right)^2+-\dfrac{5}{6}-\dfrac{3}{2}:6\)
Cho a,b,c là 3 số thực, thỏa mãn điều kiện:
a)\(\dfrac{a+b-c}{3\cdot c}=\dfrac{b+c-a}{3\cdot a}=\dfrac{c+a-b}{3\cdot b}\)
b)Tính giá trị biểu thức
\(P=\left(1+\dfrac{b}{a}\right)\cdot\left(1+\dfrac{a}{c}\right)\cdot\left(1+\dfrac{c}{b}\right)\)
\(\dfrac{3}{5}+\dfrac{\left(-1\right)}{4},\dfrac{|-3|}{5}\cdot\dfrac{4}{9}+\dfrac{\left(-4\right)}{9},\sqrt{16}+\sqrt{25}\)
Cần giúp nhanh vs
Bài 1. Tìm x
a) \(\left|x+\dfrac{7}{4}\right|=\dfrac{1}{2}\)
b) \(\left|2x+1\right|-\dfrac{2}{5}=\dfrac{1}{3}\)
c) \(3x.\left(x+\dfrac{2}{3}\right)=0\)
d) \(x+\dfrac{1}{3}=\dfrac{2}{5}-\left(-\dfrac{1}{3}\right)\)
Bài 2. Tính nhanh
\(A=\dfrac{1}{100}-\dfrac{1}{100.99}-\dfrac{1}{99.98}-\dfrac{1}{98.97}-....-\dfrac{1}{3.2}-\dfrac{1}{2.1}\)
Bài 1
\(\left(-2\right)^3.\left(\dfrac{3}{4}-0,25\right):\left(2\dfrac{1}{4}-1\dfrac{1}{6}\right)\)
Bài 2
a) \(4\dfrac{1}{3}:\dfrac{x}{4}=6:0,3\)
b) \(\left(2^3:4\right).2^{\left(x+1\right)}=64\)
Câu 1 : Cho a, b, c, d ϵ Z ; b là TB cộng của a và c
và \(\dfrac{1}{c}=\dfrac{1}{2}\left(\dfrac{1}{b}+\dfrac{1}{d}\right)\)
CMR a,b,c,d lập được thành 1 tỉ lệ thức
Câu 2 : Cho \(a_1\cdot a_3=a^2_2\) ; \(a_2\cdot a_4=a^2_3\)
CMR \(\dfrac{a_1^3+a^3_2+a_3^3}{a_2^3+a_3^3+a^3_4}=\dfrac{\left(a_1+a_2+a_3\right)^3}{\left(a_2+a_3+a_4\right)}=\dfrac{a_1}{a_4}\)
Câu 3 : Cho :
\(\dfrac{xn-ym}{p^2}=\dfrac{yp-zn}{m^2}=\dfrac{mz-xp}{n^2}\)
CMR x,y,z tỉ lệ với m,n,p
a) \(\dfrac{2}{3}\)x + 0,25 = \(-\dfrac{5}{8}\) - \(\left(\dfrac{1}{2}-\dfrac{3}{4}x\right)\)
b) ( \(9x^2\) -1 ) . ( 2x + 3 ) = 0
c) \(\left|2x-\dfrac{1}{3}\right|-\dfrac{3}{4}=\left|-\dfrac{5}{6}\right|\)
d) \(\left(0,75-\dfrac{5}{6}x\right)^3\) = \(-\dfrac{27}{64}\)
e) \(\left(\dfrac{2}{5}x-\dfrac{1}{2}\right)^2=\dfrac{9}{16}\)
f) \(\dfrac{2x-3}{3}=\dfrac{3x+2}{7}\)
h)\(\left(\dfrac{2}{3}\right)^{2x+1}\) = \(\left(\dfrac{8}{27}\right)^3\)
i) \(2.5^{3x}+5^{3x+2}=3375\)
Tìm x biết
a)\(\left(3x+\dfrac{1}{3}\right)\left(x-\dfrac{1}{2}\right)=0\)
b)\(\left(x-\dfrac{3}{2}\right)\left(2x+1\right)>0\)
c)\(\left(2-x\right)\left(\dfrac{4}{5}-x\right)< 0\)
d)\(\left(x-\dfrac{4}{7}\right):\left(x+\dfrac{1}{2}\right)>0\)
e)\(2\left(x+1\right)-\dfrac{1}{3}.\left(x-1\right)=\dfrac{2}{3}\)
k)\(\left|4x-0,2\right|=0,2\)
