\(c,\left(x+2\right)^2-\left(x-7\right)^2=3x-1\)
\(\Leftrightarrow\left(x+2-x+7\right)\left(x+2+x-7\right)=3x-1\)
\(\Leftrightarrow9.\left(2x-5\right)-3x=-1\)
\(\Leftrightarrow18x-45-3x=-1\)
\(\Leftrightarrow15x=44\Leftrightarrow x=\dfrac{44}{15}\)
\(e,\left(x-2\right)^3-\left(x+1\right)^3=9x\left(2-x\right)\)
\(\Leftrightarrow x^3-6x^2+12x-8-x^3-3x^2-3x-1=-9x^2+18x\)
\(\Leftrightarrow-9x^2+9x-9=-9x^2+18x\)
\(\Leftrightarrow-9=9x\Leftrightarrow x=-1\)
c: =>x^2+4x+4-x^2+14x-49=3x-1
=>18x-45=3x-1
=>15x=44
=>x=44/15
e: =>x^3-6x^2+12x-8-x^3-3x^2-3x-1=18x-9x^2
=>-9x^2+9x-9=-9x^2+18x
=>9x-9=18x
=>-9x=9
=>x=-1
