a) 1/7 + 3/7 : x = 5/14 b) (x^2 – 4)( x + 3/5) = 0

Đáp án + Giải thích các bước giải:

a)

`1/7 + 3/7 : x = 5/14`
`=>3/7:x=5/14-1/7`
`=>3/7:x=5/14-2/14`
`=>3/7:x=3/14`
`=>x=3/7:3/14`
`=>x=3/7*14/3`
`=>x=2`

b)

`(x^2 – 4)( x + 3/5) = 0`
`=>` \(\left[ \begin{array}{l}x^2-4=0\\x+\frac{3}{5}=0\end{array} \right.\) 
`=>` \(\left[ \begin{array}{l}x^2=0+4\\x=0-\frac{3}{5}\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x^2=4\\x=\frac{-3}{5}\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=2\\x=-2\\x=\frac{-3}{5}\end{array} \right.\)
Vậy `x∈{2;-2;(-3)/5}`