2x2=5+3x
2x2-3x-5 = 0
Вычислим дискриминант D
D = b2<span> - 4ac = ( – 3)</span>2<span> – 4·2·( – 5) = 49</span>
<span><span><span>x1 = </span><span>-b + √ D</span> = <span>3 + √ 49</span> = <span>3 + 7</span> = 10 = 5</span><span>2a2·2442</span></span><span><span><span>x2 = </span><span>-b – √ D</span> = <span>3 – √ 49</span> = <span>3 – 7</span> = -4 = -1</span><span>2a2·24<span>4</span></span></span>
-b(b+1)=(-b²-b)
(b+7)(b²-7b+49)=b³+7³ по формуле многочленов
ответ:
(-b²-b)-(b³+7³)
1,2у-1=0,4у+3
0,8у=4
у=5
Ответ: при Y=5