ta có: 30% của x = 16/5
=> x= 16/5 : 30% = 32/3
vậy x= 32/3
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tim cac gia tri cua x de bieu thuc sau co gia tri bang 0:
P(x)=2x-7+(x-14)
Q(x)=x^2-64
tim cac gia tri cua x de bieu thuc sau co gia tri bang 0:
P(x)=2x-7+(x-14)
Q(x)=x^2-64
tim gia tri cua x de cac bieu thuc sau thuc sau:
A=3x+15
B=2x^2-32 co gia tri bang 0
tim GTNN cua D=\(\frac{-15.\left|x+7\right|-68}{3.\left|x+7\right|+12}\)
6.a) tim 2 so x, ybik 7x=2y va x-y=16
b)so sanh a,b,c bik a/b=b/c=c/a
c)tim cac so a,b,cbik a/2=b/3=c/4 va a+2b-c=-20
d)cho x/2=y/5=z/7 tinh gia tri bieu thuc A=x-y+z/x+2y-z
e)cho 3x-2y/4=2z-4x/3=4y-3z/2.CMR x/2=y/3=z/4
f)cho a,b,c la cac so huu ti khac sao choa+b-c/c=a-b+c/b=-a+b+c/a
tinh gia tri bang so cua 1 bieu thuc m=(a+b)(b+c)(c+a)/abc
g)cho x/a=y/b=z/c CMRbz-cy/a=cx-az/b=ay-bx/c
tim gia tri cua bieu thuc X=2x^5-5y^3+2015 tai x,y thoa man /x-1/=(y+2)^20=0
tim nghiem cua da thuc:
M(x)=(6-3x)(-2x+5)
N(x)=x^2+x
A(x)=3x-3
Tim x,y biet
a)\(\frac{x}{y}=\frac{4}{5},\frac{x+1,2}{y}=\frac{11}{15}\)
\(\frac{x}{5}\)-\(\frac{5}{2}\) =-31. Tim x