Question

tìm số nguyên x biết

a, 11+ x =_12

b, 2-x=17-(-5)

c, x-12=(-9)-15

d.|x|-7=9

e, 9-25=(7-x)-(25+7)

Answer 1

a) \(11+x=-12\)

\(\Leftrightarrow x=-12-11\)

\(\Leftrightarrow x=-23\)

b) \(2-x=17-\left(-5\right)\)

\(\Leftrightarrow2-x=17+5\)

\(\Leftrightarrow2-x=22\)

\(\Leftrightarrow x=2-22\)

\(\Leftrightarrow x=-20\)

c) \(x-12=\left(-9\right)-15\)

\(\Leftrightarrow x-12=-24\)

\(\Leftrightarrow x=-24+12\)

\(\Leftrightarrow x=-12\)

d) \(\left|x\right|-7=9\)

\(\Leftrightarrow\left|x\right|=9+7=16\)

\(\Rightarrow\left[{}\begin{matrix}x=16\\x=-16\end{matrix}\right.\)

e) \(9-25=\left(7-x\right)-\left(25+7\right)\)

\(\Leftrightarrow-16=\left(7-x\right)-32\)

\(\Leftrightarrow-16+32=7-x\)

\(\Leftrightarrow16=7-x\)

\(\Leftrightarrow x=7-16=-9\)