Question

1) Tìm x biết:

a) 

b) 

Answer 1

\(a,2016:\left[25-\left(3x+2\right)\right]=3^2.7\)

\(\Rightarrow2016:\left[25-\left(3x+2\right)\right]=9.7\)

\(\Rightarrow2016:\left[25-\left(3x+2\right)\right]=63\)

\(\Rightarrow25-\left(3x+2\right)=2016:63\)

\(\Rightarrow25-\left(3x+2\right)=32\)

\(\Rightarrow3x+2=25-32\)

\(\Rightarrow3x+2=-7\)

\(\Rightarrow3x=-7-2\)

\(\Rightarrow3x=-9\)

\(\Rightarrow x=-9:3\)

\(\Rightarrow x=-3\)

Vậy `x = -3`

Answer 2

a: \(2016:\left[25-\left(3x+2\right)\right]=3^2\cdot7\)

=>\(2016:\left[23-3x\right]=9\cdot7=63\)

=>23-3x=2016:63=32

=>3x=23-32=-9

=>x=-3

b: \(\left(1-2+3-4+...+97-98+99\right)\cdot x=-100\)

=>\(x\cdot\left[\left(1-2\right)+\left(3-4\right)+...+\left(97-98\right)+99\right]=-100\)

=>\(x\left(-1-1-1-...-1+99\right)=-100\)

=>50x=-100

=>x=-2