1. 1) =- x² -9х+8х-72)-( x² -8х+16)=-x²+х+72- x² +8х-16=-2 x²=9х+56
2. 1) =14(x²-1)=14(х-1)(х+1)
4)=(а+2)²-х²=(а+2-х)(а+2+х)
5)=(х-а)(х+а+7)
Пусть даны две линейные функции <span>y=<span>k1</span>x+<span>m1</span></span><span> и </span><span>y=<span>k2</span>x+<span>m2</span></span>.
а) у=2х-7 и у=2х+1 - <span>параллельны</span>, <span>если </span><span><span>k1</span>=<span>k2</span>;<span>m1</span>≠<span>m2</span></span>
б) у=2х-7 и у=4х-7 - пересекаются, <span>если </span><span><span>k1</span>≠<span>k2</span></span>
в) у=2х-7 и у=2х-7 - совпадают, <span>если </span><span><span>k1</span>=<span>k2</span>;<span>m1</span>=<span>m2</span></span>
Уравнение:
2x^2 + 6x + c = 0
По теореме Виета
x1 + x2 = -b/a = -6/2 = -3
x1*x2 = c/a = c/2
1/x1 + 1/x2 = (x1 + x2) / (x1*x2) = -3 / (c/2) = -6/c = 3
c = -6/3 = -2