Период функции Т=Т1/к Т1 для sin, cos =2*П к=1/3
Т=2*П/(1/3)=6*П
(2x-3)(x+7)=(x+4)(2x-3)+3
2х"+14х-3х-21=2х"-3х+8х-12+3
4х = 12
х = 3
на всякий случай проверь )
<span>решите уравнение
1)2x²-13x+6=0
D=13²-4*2*6=169-48=121=11²
x₁=(13-11)/4=0.5
x₂=(13+11)/4=6
2)2x²-11x-21=0
D=11²+4*2*21=289=17²
x₁=(11-17)/4=-1.5
x₂=(11+17)/4=7
решите неравенства
<span>1)5x²+4x-9≤0</span>D=4²+4*5*9=196=14²
x₁=(-4+14)/10=1
x₂=(-4-14)/10=-1.8(x-1)(x+1.8)≤0
\\\\\\\\\\\\\\\\\\\\
_______-1.8_________1______________
+ - +
x∈[-1.8; 1]
</span><span><span>
2)3y²-7y-10>0
</span>D=7²+4*3*7=169=13²
y₁=(7-13)/6=-1
y₂=(7+13)/6=10/3
(y-10/3)(y+1)>0
\\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\\\\\\\\\
__________-1_____________10/3______________
+ - +
y∈(-∞; -1)∪(10/3; +∞)</span>
14!/2!.12!
14.13/2=7.13=91