4/25+15/4=(4*4)+(15*25)/100=16+375/100=391/100=3.91
( 9 - 4V5 )( 9 + 4V5 ) = 9^2 - ( 4V5 )^2 = 81 - 16•5 = 81 - 80 = 1
Ответ 1
Cos^2x - sin^2x = 0
cos2x = 0
2x = π/2 + π n, n∈Z
x = π/4 + (π n)/2, n∈Z
X^2-6x+9
25-x^2
36x^2-12x+1
36x^2-4
4+16a+16a^2
9b^2-1
49x^2-56x+16
162x^2+36x
(7+2a)=49a^2+28a+4b^2