Giải hộ mình câu này với các bạn

a)

$\left(x+5\right)^2-\left(x-5\right)^2-2x+1=0$

$\left(x+5-x+5\right)\left(x+5+x-5\right)-2x+1=0$

$10.2x-2x+1=0$

$20x-2x+1=0$

$18x=-1$

$x=-\frac{1}{18}$

Vậy $x=-\frac{1}{18}.$

b)

$\left(2x-7\right)^2-\left(x+3\right)^2=3x^2+6$

$4x^2-28x+49-x^2-6x-9=3x^2+6$

$3x^2-34x+40=3x^2+6$

$-34x=-34$

$x=1$

Vậy $x=1.$

c)

$\left(3x+2\right)^2-9\left(x-5\right)\left(x+5\right)=225-5x$

$9x^2+12x+4-9\left(x^2-25\right)=225-5x$

$9x^2+12x+4-9x^2+225=225-5x$

$12x+229=225-5x$

$17x=-4$

$x=-\frac{4}{17}$

Vậy $x=-\frac{4}{17}.$