1) giải phương trình
a) x - \(\dfrac{\dfrac{x}{2}-\dfrac{3+x}{4}}{2}\)= 2x - \(\dfrac{\dfrac{10-7x}{3}}{2}\)- x-1
b) (2x-2)\(^2\)= (x+1)\(^2\)+3(x-2)(x+3)
c) \(\dfrac{x-90}{10}+\dfrac{x-76}{12}+\dfrac{x-58}{14}+\dfrac{x-36}{16}+\dfrac{x-15}{17}=15\)