Question

Solve: 25z^2-16=0

Answer 1

@dpasingh

Answer 2

this is the difference of 2 perfect squares

use the identity

a^2 - b^2 = (a + b)(a - b)

here a = 5z and b = 4

Answer 3

\[\huge 25z^2-16=0 \rightarrow (5z)^2 - 4^2\]
\[\huge \rightarrow (5z +4) (5z-4) =0\]
\[\huge \rightarrow (5z +4)=0 ---or (5z-4) =0\]
\[\huge z= -4/5 , 4/5\]