Question

СРОЧНО АЛГЕБРА 7 КЛАСС 1 ВАРИАНТ 50 БАЛОВ!!!!

Answer 1

а)  2/7 * x²y * 3/4х³ * 7у² = 21у/14х= 3у/2х

б)  (2m³n^4 )³ * 5m²n = 8m^9 n^12 * 5m²n = 40m^11 n^13

5m³ - 3n² + 2mn - 8m³ - mn + 7n² = -3m³ + 4n² + mn = -3(-2)³ + 4 + (-2) = 24 + 4 - 2 = 26

a)  (2a - 5b) + (-3a + 2b) = 2a - 5b - 3a + 2b = -a - 3b

б)  (-2x² - 3x + 4) - ( -2x² + 7x - 6) = -2x² - 3x + 4 + 2x² - 7x + 6 = -10x + 10

А Б В

3 2 1

а) (2x - 1) + (-x +5) = 2

2x - 1 - x + 5 = 2

x + 4 = 2

x = -2

б)  (43 - 12x) - (-7x + 33) = -2

43 - 12x + 7x - 33 = -2

10 - 5x = -2

-5x = -2 - 10

- 5x = -12

x = 2,4 ( или 2 2/5)

в)  x² + (5x - 2) - (3x + 1) = 3x + x²

x² + 5x - 2 - 3x - 1 = 3x + x²

x² + 2x - 3 = 3x + x²

x² + 2x - 3x - x² = 3

-x = 3

x = -3

Answer 2

1.

$a)\frac{2}{7}x^2y\cdot \frac{3}{4}x^3\cdot 7y^2=x^2y\cdot \frac{3}{2}x^3y^2=\frac{3}{2}x^5y^3\\ b)(2m^3n^4)^3\cdot 5m^2n=8m^9n^1^2\cdot 5m^2n=40m^1^1n^1^3$

2.

$5m^3 - 3n^2 + 2mn - 8m^3 - mn + 7n^2 = -3m^3 + 4n^2 + mn = -3(-2)^3 + 4 + (-2) = 24 + 4 - 2 = 26$

3.

$a)(2a-5b)+(-3a+2b)=2a-5b-3a+2b=-a-3b\\ b)(-2x^2-3x+4)-(-2x^2+7x-6)=-2x^2-3x+4+2x^2-7x+6=-10x+10$

4. А-3; Б-2; В-1

5.

$a)(2x-1)+(-x+5)=2\\ 2x-1-x+5=2\\ x+4=2\\ x=2-4\\ x=-2\\ b)(43-12x)-(-7x+33)=-2\\ 43-12x+7x-33=-2\\ 10-5x=-2\\ -5x=-2-10\\ -5x=-12\\ x=\frac{12}{5}\\ B) x^2+(5x-2)-(3x+1)=3x+x^2\\ 5x-2-3x-1=3x\\ 2x-3=3x\\ 2x-3x=3\\ -x=3\\ x=-3$