8*15=120 тг стоят булочки
210-120=90 стоят пирожки
90/30=3 пирожка
Ответ: продали 3 пирожка
1
a)c{-3;6}⇒1/3c{-1;2}
b{2;-2}⇒-b{-2;2}
a=1/3c-b={-3;4}
б)/a/=√(9+16)=√25=5
в)a=-3i+4j
2
AB=
![\sqrt{(0+4)^2+(1-1)^2} = \sqrt{16+0} = \sqrt{16} =4](https://tex.z-dn.net/?f=+%5Csqrt%7B%280%2B4%29%5E2%2B%281-1%29%5E2%7D+%3D+%5Csqrt%7B16%2B0%7D+%3D+%5Csqrt%7B16%7D+%3D4)
BC=
![\sqrt{(-2-0)^2+(4-1)^2} = \sqrt{4+9} = \sqrt{13}](https://tex.z-dn.net/?f=+%5Csqrt%7B%28-2-0%29%5E2%2B%284-1%29%5E2%7D+%3D+%5Csqrt%7B4%2B9%7D+%3D+%5Csqrt%7B13%7D+)
CD=
![\sqrt{(-6+2)^2+(4-4)^2} = \sqrt{16+0} = \sqrt{16} =4](https://tex.z-dn.net/?f=+%5Csqrt%7B%28-6%2B2%29%5E2%2B%284-4%29%5E2%7D+%3D+%5Csqrt%7B16%2B0%7D+%3D+%5Csqrt%7B16%7D+%3D4)
AD=
![\sqrt{(-6+4)^2+((4-1)^2}= \sqrt{4+9} = \sqrt{13}](https://tex.z-dn.net/?f=+%5Csqrt%7B%28-6%2B4%29%5E2%2B%28%284-1%29%5E2%7D%3D+%5Csqrt%7B4%2B9%7D+%3D+%5Csqrt%7B13%7D++)
AB=CD U BC=AD⇒ABCD-параллелограмм
P=2(AB+BC)=2(4+√13)=8+2√13
3
AB{2-m;6} ,BC{-3;6}
AB=BC⇒2-m=-3⇒m=2+3=5
273985:1=273985 Второе) 175:1=175<span> </span>
7,54к-3,6к = 5,91;
3,94к = 5,91;
к = 1,5
Ответ: к = 1,5