The sum of three numbers is 19. Two times the first number increased by six times the second number plus the third number is 12. The sum of three times the first number and eight times the second number, increased by the third number is -14. If the first number is represented by x, the second
number is represented by y, and the third number is repre d by z, which of the systems of equations below can be used to determine the three
numbers?
Please help due tonight!!

Step-by-step explanation:

 x+    y+z=19   ...(1)

2x+6y+z=12   ...(2)

3x+8y+z=-14    ...(3)

(2)-(1) gives

x+5y =-7   ...(4)

(3)-(1)  gives

2x+7y= -33   ...(5)

multiply (4) by 2

2x+10y=-14   ...(6)

(6)-(5) gives

3y=19

y=19/3

x+95/3=-7

x=7+95/3=(21+95)/3=116/3

from (1)

116/3+19/3+z=19

(116+19)/3+z=19

135/3+z=19

45+z=19

z=19-45=-26

15

step-by-step explanation:

we are given the following expression and we are to solve it and find the product:

-13 × (-5)

solving the given expression in the standard order of solving a mathematical expression, beginning with the opening of brackets and then multiplying the terms and changing their signs.

-3 × -5 = 15 (answer is positive because when negative is multiplied with negative, it gives a positive answer)

pentagon

step-by-step explanation:

the coordinates   a(5, -2), b(3,-1),c(-4,-4) d(-3,8) and e(-1,4) forms the vertices of the polygon when they are connected in order.

in order to classify that which polygon is it with the given coordinates, first count the number of vertices and then count the number of sides it can make with these vertices.

since, the given coordinates have five vertices, therefore, it will make five sides. moreover, pentagon is regular in nature therefore it will be convex.

now, a polygon with five sides is known as pentagon, therefore, the given polygon is the pentagon.