6. Решите уравнение. а) (5х-2)(5х+2)-(5х-1)2=4; б) 100х2-16=0

[latex] (5x-2)(5x+2)-(5x-1)^2=4 \\ 5x-1=t \\ (t-1)(t+3)-t^2=4 \\ t^2+3t-t-3-t^2=4 \\ t^2+2t-3-t^2=4\\ 2t-3=4 \\ 2t=7 \\ t=3,5 \\ 5x-1=3,5 \\ 5x=4,5 |:5 \\ x=0,9 \\ [/latex] ------------- [latex] 100x^2-16=0 \\ (10x)^2-4^2=0 \\ (10x-4)(10x+4)=0 \\ 10x-4=0; 10x=4 |:10 ; x=0,4 \\ 10x+4=0; 10x=-4 :10; x=-0,4 \\ [/latex]