Question

Tìm giá trị của số nguyên X sao cho 4 * ( x - 8 )bé hơn 0

b )   -3(x*2) bé hơn 0

Answer 1

a ) \(4.\left(x-8\right)< 0\)

\(\Leftrightarrow4x-32< 0\)

\(\Leftrightarrow4x< 32\)

\(\Leftrightarrow x< 8\)

b ) \(-3\left(x.2\right)< 0\)

\(\Leftrightarrow-6x< 0\)

\(\Leftrightarrow x>0\)

Answer 2

\(\text{a) }4\left(x-8\right)< 0\)

\(\Leftrightarrow x-8< 0\div4\)

\(\Leftrightarrow x-8< 0\)

\(\Leftrightarrow x< 0+8\)

\(\Leftrightarrow x< 8\)

\(\Rightarrow x\in\left\{...;0;1;2;3;4;5;6;7\right\}\)

\(\text{b) }-3\left(2x\right)< 0\)

\(\Leftrightarrow2x< \frac{0}{-3}\)

\(\Leftrightarrow2x< 0\)

\(\Leftrightarrow x< 0\div2\)

\(\Leftrightarrow x< 0\)

\(\Rightarrow\hept{\begin{cases}x\inℤ\\x\notinℕ^∗\end{cases}}\)