=(-2sin30*sin20)/sin20=-1
<span>(3x-1)^2 = 2x^2+4x +9
9x</span>²-6x+1=2x²+4x+9
<span>
7x</span>²-10x-8=0
<span>
x1=[ 5-</span>√(25+56)]/7 =(5-9)/7= -4/7
x1=[ 5+√(25+56)]/7 =(5+9)/7=2
1. -6x^2+31x+7
2. -20a^2+26a+21
3. 5x^2-10x
4. 7y^4-6y^6+3y^3+6y^5
5/ -4a^5+15a^3-4a^2+4a-a^4
6. 16b^4-10b^3-30b^2
7.l 16x^3-20x^2+1.5x-9x^4
8. -10xy^2+2xy-8y^3+8y^2-9
9. 6a^5+3a^4-2a^3+8a
1)-300*(-50+30)=-300*(-20)=6000
ответ 6000
2)60 000 - 100%
х - 25%
х=(60000*25)/100=15000
ответ 15000
A- prostinya b=2a pododeyanik c= a-80- navolochka
a+2a+a-80=8m
4a-80=800
4a=880
a=220
b= 440
c=160