Đáp án:
Giải thích các bước giải:
`b,(3x^2+10x-8)=(5x^2-2x+10)^2`
`=>(3x^2+10x-8)-(5x^2-2x+10)^2=0`
`=>(3x^2+10x-8-5x^2+2x-10)(3x^2+10x-8+5x^2-2x+10)=0`
`=>(-2x^2+12x-18)(8x^2+8x+2)=0`
`=>2(x-3)^2(2x+1)^2=0`
\(\left[ \begin{array}{l}x=3\\x=-1/2\end{array} \right.\)
`e,(x+1)^2=4(x^2-2x+1)`
`=>(x+1)^2-[2(x-1)]^2=0`
`=>(x+1-2x+2)(x+1+2x-2)=0`
`=>(-x+3)(3x-1)=0`
\(\left[ \begin{array}{l}x=3\\x=1/3\end{array} \right.\)
`f,(x^2-9)^2-9(x-3)^2=0`
`=>(x^2-9-3x+9)(x^2-9+3x-9)=0`
`=>(x^2-3x)(x^2+3x-18)=0`
`=>x(x-3)^2(x+6)=0`
\(\left[ \begin{array}{l}x=0\\x=-6\\x=3\end{array} \right.\)
`i,(2x-1)^2=49`
\(\left[ \begin{array}{l}2x-1=7\\2x-1=-7\end{array} \right.\)
\(\left[ \begin{array}{l}x=4\\x=-3\end{array} \right.\)
còn lại làm giống câu b
theo dạng :
`A^2-B^2=(A+B)(A-B)`
