Đáp án:
`a)` \(\left[ \begin{array}{l}x=-2\\x=\frac{1}{3}\end{array} \right.\)
`b)` \(\left[ \begin{array}{l}x=2\\x=-5\end{array} \right.\)
Giải thích các bước giải:
`a) (5x-4)^2-49x^2=0`
`<=> (5x-4)^2-(7x)^2=0`
`<=> (5x-4-7x)(5x-4+7x)=0`
`<=> (-2x-4)(12x-4)=0`
`<=> -8(x+2)(3x-1)=0`
`<=>` \(\left[ \begin{array}{l}x+2=0\\3x-1=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=-2\\x=\frac{1}{3}\end{array} \right.\)
`x^2+3x-10=0`
`<=> x^2-2x+5x-10=0`
`<=> x(x-2)+5(x-2)=0`
`<=> (x-2)(x+5)=0`
`<=>`\(\left[ \begin{array}{l}x-2=0\\x+5=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=2\\x=-5\end{array} \right.\)
