<span>"0" - абсолютное число</span>
(600-100)-200=300
1)600-100=500
<span>2)500-200=300
надеюсь помогло</span>
1) x^2 + 4x<span> - 21 = 0
D = </span>4^2<span> - 4·1·(-21) = 16 + 84 = 100
</span>x1 = (<span><span>-4 - √100)/</span>2·1</span> = (<span>-4 - 10)/2</span> = <span>-14/2</span><span> = -7
</span>x2 = (<span><span>-4 + √100)/</span>2·1</span> = (<span>-4 + 10)/2</span> = <span>6/2</span><span> = 3
</span>2) 2x^2 + 10x<span> = 0
</span>D = 10^2<span> - 4·2·0 = 100 - 0 = 100
</span>x1 = (<span><span>-10 - √100)/</span>2·2</span> = (<span>-10 - 10)/4</span> = <span>-20/4</span><span> = -5
</span>x2 = (<span><span>-10 + √100)/</span>2·2</span> = (<span>-10 + 10)/4</span> = <span>0/4</span><span> = 0
</span>3) x^2 + 3x<span> - 18 = 0
</span>D = 3^2<span> - 4·1·(-18) = 9 + 72 = 81
</span>x1 = (<span><span>-3 - √81)/</span>2·1</span> = (<span>-3 - 9)/2</span> = <span>-12/2</span><span> = -6
</span>x2 = (<span><span>-3 + √81)/</span>2·1</span> = (<span>-3 + 9)/2</span> = <span>6/2</span><span> = 3
</span>4) 5x^2 + 15x<span> = 0
</span>D = 15^2<span> - 4·5·0 = 225 - 0 = 225
</span>x1 = (<span><span>-15 - √225)/</span>2·5</span> = (<span>-15 - 15)/10</span> = <span>-30/10</span><span> = -3
</span>x2 = (<span><span>-15 + √225)/</span>2·5</span> = (<span>-15 + 15)/10</span> = <span>0/10</span><span> = 0</span>
<span>5) x = -20
</span>
Здесь наднадо череерез дроби решатрешать, 3,5=3 1/2=7/2 1 1/4=5/4 7/2:5/4=7/2*4/5=14/5 1,4=1 4/10=7/5 7/5-14/5=-7/5 3,4=3 2/5=17/5 2 1/8=17/8 17/5:17/8=17/5*8/17=8/5 -7/5+8/5=1/5
Х-2х=-3/7-1/5
-х=-3
х=3
Ответ: корень уравнения 3