помогите решить уровнения 8х + 0,77=4,61 - 8х (х+1)(х+2)-(х+3)(х+4)=0 ... - Все ответы

Дано ответов: 2

Правильный ответ

1) $8x+0,77=4,61-8x$

$8x+8x=4,61-0,77$

$16x=3,84$

$x=3,84:16$

$x=0,24$

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$8\cdot0,24+0,77=4,61-8\cdot0,24$ (это проверка)

1,92+0,77=4,61-1,92

2,69=2,69

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2) $(x+1)(x+2)-(x+3)(x+4)=0$

$x^{2}+2x+x+2-(x^{2}+4x+3x+12)=0$

$x^{2}+2x+x+2-x^{2}-4x-3x-12=0$

$(x^{2}-x^{2})+(2x+x-4x-3x)+(2-12)=0$

$-4x-10=0$

$4x=-10$

$x=-10:4$

$x=-2,5$

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$(-2,5+1)(-2,5+2)-(-2,5+3)(-2,5+4)=0$

$-1,5\cdot(-0,5)-(0,5)\cdot1,5=0$

$0,75-0,75=0$

$0=0$

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3) $(x-2)(x-3)-(x-1)(x-4)=0$

$x^{2}-3x-2x+6-(x^{2}-4x-x+4)=0$

$x^{2}-3x-2x+6-x^{2}+4x+x-4=0$

$(x^{2}-x^{2})+(-3x-2x+4x+x)+(6-4)=0$

$2=0$

корней нет

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4) $10x^{2}-(2x-3)(5x-1)=31$

$10x^{2}-(10x^{2}-2x-15x+3)=31$

$10x^{2}-10x^{2}+2x+15x-3=31$

$10x^{2}-10x^{2}+2x+15x-3-31=0$

$(10x^{2}-10x^{2})+(2x+15x)+(-3-31)=0$

$17x-34=0$

$17x=34$

$x=34:17$

$x=2$

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$10\cdot2^{2}-(2\cdot2-3)(5\cdot2-1)=31$

$40-(1\cdot9)=31$

$40-9=31$

$31=31$

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5) $12x^{2}-(4x-3)(3x+1)=-2$

$12x^{2}-(12x^{2}+4x-9x-3)=-2$

$12x^{2}-12x^{2}-4x+9x+3=-2$

$12x^{2}-12x^{2}-4x+9x+3+2=0$

$(12x^{2}-12x^{2})+(-4x+9x)+(3+2)=0$

$5x+5=0$

$5x=-5$

$x=-5:5$

$x=-1$

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$12\cdot(-1)^{2}-(4\cdot(-1)-3)(3\cdot(-1)+1)=-2$

$12-(-4-3)\cdot(-3+1)=-2$

$12-(-7\cdot(-2))=-2$

$12-14=-2$

$-2=-2$

Svet1ana_zn (172k баллов) 29 Янв, 18