\(\dfrac{1}{2}a=\dfrac{2}{3}b=\dfrac{3}{4}c\) và a-b=15
2) xác định hệ số a,b của đa thức
P(x)= ax+b, biết
a) P(1)= \(\dfrac{-5}{3}\)
b) P(\(\dfrac{-1}{2}\)) = \(\dfrac{4}{3}\)
Cho a ; b ;c tm : \(\dfrac{a}{x}=\dfrac{b}{x+1}=\dfrac{c}{x+2}\) . CM : 4.(a-b).(b-c)= (a-c)2
Cho a ; b \(\ne\) 0 tm : \(\dfrac{ab+1}{b}=\dfrac{bc+1}{c}=\dfrac{ca+1}{a}\) . Cm : \(a^{2017}+\dfrac{1}{b^{2018}}=b^{2017}+\dfrac{1}{c^{2018}}=c^{2017}+\dfrac{1}{a^{2018}}\)
Bài 1: Tìm x, biết:
a) \(\dfrac{x+2}{18}\)=\(\dfrac{x-5}{9}\)
b)\(\dfrac{x+2}{-20}\)=\(\dfrac{-5}{x+2}\)
c) -10+\(\left(2x-5\right)^3\)=17
Bài 2: Tìm x,y,z biết:
a) \(\dfrac{x}{12}\)=\(\dfrac{y}{-5}\)=\(\dfrac{z}{6}\) và 2x+y-3z=26
b) \(\dfrac{x}{2}\)=\(\dfrac{y}{5}\)=\(\dfrac{z}{4}\) và x.y.z=40
c) \(\dfrac{x+1}{3}\)=\(\dfrac{y+2}{4}\)=\(\dfrac{z+3}{5}\) và x+y+z=18
d) \(\dfrac{x}{2}\)=\(\dfrac{y}{5}\); \(\dfrac{y}{4}\)=\(\dfrac{z}{6}\) và x+y-z=26
e) 4x=3y và \(x^2\)+\(y^2\)=100
1)
a) Tính A = \(1+\dfrac{3}{2^3}+\dfrac{4}{2^4}+\dfrac{5}{2^5}\)
Tính và tìm x:
a) \(\dfrac{-1}{4}\).13\(\dfrac{9}{11}\) - 0,25 . 6\(\dfrac{2}{11}\)
b) \(\dfrac{31}{9}\). /x/ - \(\dfrac{5}{2}\) = \(\dfrac{8}{3}\)
Tìm x ∈ Z, biết:
a, \(\dfrac{3}{2}\). 4x + \(\dfrac{5}{3}\). 4x+2 = \(\dfrac{3}{2}\). 48 + \(\dfrac{5}{3}\). 410
b, (1/3 + 1/6) . 2x + 2x+1 = 212 + 210
c, (1/2 - 1/3 ) . 6x + 6x+2 = 615 + 618
d, \(\dfrac{5}{3}\). 8x+2 - \(\dfrac{3}{5}\) . 8x = \(\dfrac{5}{3}\). 811 - \(\dfrac{3}{5}\). 89
bài 1 tìm x thuộc Q biết
a. |x|=\(^1_53\) và x<0
b.|x|=-2,1
c.|x-3,5|=5
d. |x+\(\dfrac{3}{4}\)|-\(\dfrac{1}{2}\)=0
e. |x-\(\dfrac{2}{5}\)|+\(\dfrac{1}{2}\)=\(\dfrac{3}{4}\)
f. \(\dfrac{5}{6}\)-|2-x|=\(\dfrac{1}{3}\)
g. (2x-5)^2=9
h. \(\sqrt{3-7x}\)=\(\dfrac{1}{4}\)
i. (\(\dfrac{2}{3}\))^x=\(\dfrac{8}{27}\)
k. (x+\(\dfrac{1}{2}\))^2=\(\dfrac{1}{9}\)
l. \(\dfrac{\left(-3^x\right)}{81}\)=-27
m.\(\left(x-2\right)\)^2x+3=(x-2)^2x+1(x thuộc N)