Question

4)tìm x:

a) 25 - ( 25 - x ) = 12 + ( 42 - 65 )

b) 215 + (-38) - 54 + 90 - ( -48 + x )=0

c) 15 - ( 15 + x ) = 21

d) 39 + ( x - 39 ) = 50

e) 13 - ( 25 - x)=7

g) x - 15 = -21

i) 12 - (30-x)= -23

k) 31 - ( 17+x) = 18

m) |x| - 5 = 12

Answer 1

a) \(25-\left(25-x\right)=12+\left(42-65\right)\)

\(25-\left(25-x\right)=12+\left(-23\right)\)

\(25-\left(25-x\right)=-11\)

\(25-x=25-\left(-11\right)\)

\(25-x=36\)

\(x=25-36\)

\(x=-11\)

Answer 2

Làm 2 câu dài cho bạn nhá! Mấy câu ngắn tương tự!

a, \(25-\left(25-x\right)=12+\left(42-65\right)\)

\(\Rightarrow25-25+x=12+42-65\)

\(\Rightarrow x=-11\)

b, \(215+\left(-38\right)-54+90-\left(-48+x\right)=0\)

\(\Rightarrow215-38-54+90+48-x=0\)

\(\Rightarrow x=261\)

m, \(\left|x\right|-5=12\)

\(\Rightarrow\left|x\right|=17\Rightarrow\left\{{}\begin{matrix}x=-17\\x=17\end{matrix}\right.\)

Chúc bạn học tốt!!!