<span>2а( а + в – с) – 2в( а –в – с) + 2с( а – в + с)= </span>
=
=2(
)
8(3x-1)-4(2+4x)=(24x-8)-(8+16x)=24x-8-8-16x=8x-16=8(x-2)
192080 !!!!!!!!!!!!!!!!!!!
(1-sin2a)/(1-2sin²a)=(cosa-sina)²/cos2a=(cosa-sina)²/(cos²a-sin²a)=
=(cosa-sina)²/(cosa-sina)(cosa+sina)=(cosa-sina)/(cosa+sina)
tg(π/4-a)=sin(π/4-a)/cos(π/4-a)=
=(sinπ/4cosa-cosπ/4sina)/(cosπ/4cosa+sinπ/4sina)=
=(√2/2cosa-√2/2sina)/(√2/2cosa+√2/2sina)=
=√2/2*cosa-sina)/√2/2(cosa+sina)=(cosa-sina)/(cosa+sina)
(cosa-sina)/(cosa+sina)=(cosa-sina)/(cosa+sina)
15x²+4=16x
15x²-16x+4=0
D=16²-4*15*4=256-240=16
x=(16+4)/2*15=20/30=2/3
x=(16-4)/2*15=12/30=2/5
7x²=4x-3
7x²-4x+3=0
D=4²-4*7*3<0 => x∈∅
2x-5x²=0
x(2-5x)=0
x=0, 2-5x=0
x=0, 5x=2
x=0, x=0,4
5x²-20=0/:5
x²-4=0
x²=4
x=2, x=-2
7x+3+4x²=0
4x²+7x+3=0
a-b+c=0 (4-7+3=0) => x=-1, x=-3/4=-0,75
x²-9x+18=0
D=9²-4*18=81-72=9
x=(9+3)/2=12/2=6
x=(9-3)/2=6/2=3
16k²+9-24k=0
16k²-24k+9=0
D=24²-4*16*9=576-576=0
k=24/2*16=24/32=6/8=3/4=0,75