√3sin870°-2cos(-855°)+ √3ctg930°

Question

Алгебра: √3sin870°-2cos(-855°)+ √3ctg930°​

1saridua1 · Accepted Answer

№1.
1) 5x^2 + 5 = 5 - 30x;
5x^2 + 30 x = 0;
5x(x+6) = 0;
x1 = 0; x2 = - 6.
2) x^2 - 14x + 30 = - x^2 - 21 x + 39;
2x^2 +7x - 9 = 0;
D = 49+72 = 121= 11^2;
x1 = - 9;
x2 = 1.
3)1/2*x^2 + 7x + 12= 0;
x^2 + 14x + 24 = 0;
D = 196- 96 = 100 = 10^2;
x1 = -2;
x2 = - 12.
4) (-x-4)(x+3) =0;
- x-4 = 0;⇒ x = -4;
x+3 = 0; ⇒ x = 3.

2.
6 x - 7 > 7x +8;
6x - 7x > 8 +7;
-x > 15;
x < - 15.
3.
{-35 +5x >0; { 5x > 0+35; {5x> 35; { x > 7;
6 - 3x > -3; - 3x > -3-6; -3x > - 9; x < 3 ⇒ х пустое множество, решений нет

√3sin870°-2cos(-855°)+ √3ctg930°​

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