sina tga ctga =sina =0,5, tga ctga=1
X^2 - 14x + 13 = 0
x1 + x2 = 14
x1 * x2 = 13
--------------------------
x^2 + 12x + 35 = 0
x1 + x2 = - 12
x1 * x2 = 35
----------------------------
7x^2 - 2x - 14 = 0
x1 + x2 = 2 / 7
x1 * x2 = ( - 14 ) / 7 = - 2
<span>(y - a)(y - b) = y</span>² <span>- (a + b) *y + ab,
</span>(y - a)(y - b) = y² - ya - yb + ab,
(y - a)(y - <span>b) = y * (y - a) - b * (y - a),
</span>(y - a)(y - b) = (y - a)(y - <span>b)</span>
Домножим обе части уравнения на 54:
9 * 7x - 3 * 5x = 4 * 2
63x - 15x = 8
48x = 8
x = 8/48
x = 1/6
Ответ: x = 1/6
0,01 в минус первой это 100. 100-165 = -65