Cosx(2sinx-√2)=0
cosx=0⇒x=π/2+πn
sinx=√2/2⇒x=(-1)^n*π/4+πn
x=11π/4;5π/2;7π/2
4( x - 1)² = 12x + 3
4( x² - 2x + 1) = 12x + 3
4x² - 8x + 4 = 12x + 3
4x² - 8x - 12x + 4 - 3 = 0
4x² - 20x + 1 = 0
D = b² - 4ac = 400 - 4×4 = 400 - 16 = 384
x1,2 = ( 20 +/- √384) / 8
Площадь а×б
7×3
периметр {а+б}×2
()7+3)×2
= у² +14у +49 -у² +6у = 20у +49 = 20·(-1/20) +49 = -1 +49 = 48