Вопрос от посетителя
ПОМОГИТЕ РЕШИТЬ ПОЖАЛУЙСТО РЕБЯТА
1. 1) X(2X+3)-8=2X^2 +11X
2) 7X- (3X-1)^2=10-(3X-1)(3X+1)
3)X+((X+10)/5)=((X-2)/3)
4)((2X-0.5)/3)+((X-2)/40=0.5
5)(3*((2/4)*X)-((10X-7)/12)=2.5X
2.
1)2X^2+9X+4=0
2)19X^2-76=0
3)((1/6)*X^2)-((13/6)*X)+7=0
4) ((2*(1/3)*X^2)-((3*(1/2)*X=0
РЕБЯТА ПОМОГИТЕ ПОЖАЛУСТО ОЧЕНЬ НУЖНО ЗА РАНЕЕ ОГРОМНОЕ СПАСИБО
Отвечает Илюха:
1. 1) x(2x + 3) – 8 = 2x^2 + 11x
2x^2 + 3x – 8 = 2x^2 + 11x
-8 = 11x – 3x = 8x
x = -1
2) 7x – (3x-1)^2 = 10 – (3x-1)(3x+1)
7x – (9x^2 – 6x + 1) = 10 – (9x^2 – 1)
7x – 9x^2 + 6x – 1 = 10 – 9x^2 + 1
7x + 6x = 10 + 1 + 1
13x = 12
x = 12/13
3) x + (x + 10)/5 = (x – 2)/3
Умножаем все на 15
15x + 3(x + 10) = 5(x – 2)
15x + 3x + 30 = 5x – 10
18x – 5x = -10 – 30
13x = -40
x = -40/13
4) (2x – 0,5)/3 + (x – 2)/40 = 0,5
Умножаем все на 120
40(2x – 0,5) + 3(x – 2) = 60
80x – 20 + 3x – 6 = 60
83x = 60 + 20 + 3 = 86
x = 86/83
5) 3*(2/4)*x – (10x – 7)/12 = 2,5x
3x/2 – (10x – 7)/12 = 2,5x
Умножаем все на 12
3x*6 – (10x – 7) = 2,5x*12
8x + 7 = 30x
7 = 30x – 8x = 22x
x = 7/22
2. 1) 2x^2 + 9x + 4 = 0
D = 9^2 – 4*2*4 = 81 – 32 = 49 = 7^2
x1 = (-9 – 7)/4 = -16/4 = -4; x2 = (-9 + 7)/4 = -2/4 = -1/2
2) 19x^2 – 76 = 0
x^2 = 76/19 = 4
x1 = -2; x2 = 2
3) (1/6)*x^2 – (13/6)*x + 7 = 0
Умножаем все на 6
x^2 – 13x + 42 = 0
D = 13^2 – 4*1*42 = 169 – 168 = 1 = 1^2
x1 = (13 – 1)/2 = 12/2 = 6; x2 = (13 + 1)/2 = 14/2 = 7
4) (2/3)*x^2 – (3/2)*x = 0
Умножаем все на 6
4x^2 – 9x = 0
x(4x – 9) = 0
x1 = 0; x2 = 9/4