Sin26/sin12-sin54/si78=sin26/sin12-cos26/cos12=
=(sin26cos12-cos26sin12)/sin12cos12=sin(26-12):1/2sin24=2sin14/sin24
Графики и решение во вложении.
<span>(2а+в)²-(2а-3в)(3в+2а)-10в² =4а²+4ав+в²-4а²+9в²-10в²=4ав=4*1/4*3=3
</span>(х-3)(6х+5)=(х-3)(2х-3)
6х²-18х+5х-15=2х²-6х-3х+9
6х²-2х²-13х+9х-15-9=0
4х²-4х-24=0
х²-х-6=0
D=1+24=25
х₁=(1+5)/2=3
х₂=(1-5)/2=-2
А) 2a²
б) -√(7c)²= -Ι 7c Ι=7c