√(-4)² -√(-x) =5 ; * * *4 -√ (-x) =5 где √(-x) ≥0 ⇒ x ∉ <span>∅ ; 4 - 5 =</span>√... <span>* * *</span>
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√(-4)² -√(-x) =5 ;⇔√(-x) =4 - 5⇒√(-x) = -1 ;
(2+√5)^2-(2-√5)^2)/
/(2^3*√5^3)=
(4+4*√5+5-(4-4*√5+5))/
/(40*√5)=
=(9+4*√5-9+4*√5)/40*√5=
8*√5/40*√5=√5/5*√5=1/5
cos60*cos(35+25)=cos^2(60)=1/4
1/7x^2-7=0
1/7x^2=7
x^2=49
x1=-7 x2=7