1. - 3x² = - 18
3x² = 18
x² = 6
x = √6
<span>x = - √6
3.</span>D=b^2-4ас=9+40=4
х1=(-3-7) : 10=-1<span>
х2=(-3+7) : 20 =0,4</span><span>
4.</span>5x^2-8x+3=0
D=8^2- 4*3*5=64-60=4
x1=(8+ корень из 4)/10= 1
x2=(8-2)/10=0,6
5. 2*X^2-x-6=0 - квадратное уравнение, решаем:
D=(-1)^2-4*2*(-6)=49
x=(1 +- 7)//2*2
совокупность:
x=(1+7)//2*2
<span>x=(1-7)//2*2</span>
<span>x=2</span>
x=-1,5
<span>ответ:-1,5; 2.</span>
1) 7(x + 1) - 2(x - 4) = x - 9
7x + 7 - 2x + 8 = x - 9
5x - x = - 9 - 15
4x = - 24
x = - 6
2) 3(x - 1) - 2(x - 5) = 5x + 13
3x - 3 - 2x + 10 = 5x + 13
x - 5x = 13 - 7
- 4x = 6
x = - 1,5
3) 2 = (3x - 5) - (7 - 4x)
2 = 3x - 5 - 7 + 4x
2 = 7x - 12
7x = 2 + 12
7x = 14
x = 2