a) (2x-5)2-(2x-3)(2x+3)=5
(2x-5)2-[(2x)2-32 ]=5
(2x-5)2-(2x)2+9=5
[(2x-5)-(2x)][(2x-5)+2x]=5-9
(2x-5-2x)(2x-5+2x)=-4
-5(4x-5)=-4
4x-5=-4:-5
4x-5=\(\dfrac{4}{5}\)
4x=\(\dfrac{4}{5}\)+5
4x=\(\dfrac{29}{5}\)
x=\(\dfrac{29}{5}\):4
x=\(\dfrac{29}{20}\)
vậy x=\(\dfrac{29}{20}\)