7-4 = a(1-2)+b(1+3)
3= -a + 4b
a =4 b - 3
-7-4 = a(-1-2) +b(-1+3)
-11 = -3a+2b
-11= -3(4b-3) + 2b
-11 = -12 b + 9 + 2b
-11-9= -10b
-20=-10b
<u>b=2</u>
a= 4*2 - 3
<u>a= 5</u>
Вроде,так..............................
2x^2 - 11x - 21 = 0
Решим квадратное уравнение через дискриминант
D = b^2 - 4ac = (-11)^2 - 4*2*(-21) = 121 + 168 = 289 = 17^2
x₁ = ( 11 + 17)/4 = 28/4 = 7;
x₂ = ( 11 - 17)/4 = - 6/4 = - 3/2 = - 1,5;
Ответ
- 1,5; 7
27.2-18.91÷(2.4+3.72)=
=27.2-18.91÷6.12=
=27.2-3.0=
=24.2
<span>9x^3-27x^2=0</span>
9x^2(x-3)=0
x=0
x=3