Resuelve el siguiente sistemas de ecuaciones por el método de sustitución
83x - 20y = 590
60x + 18y = 816

x=10 and y=12

Step-by-step explanation:

To solve this quadratic equation we will use two method

1. Elimination method

2. substitution method

first of we use elimination method

we either eliminate x or y

we will be eliminating y

83x-20y=590(eq1)

60x+18y=816(eq2)

y will be eliminated by multiplying

(eq1) by 9

(eq2) by 10

which will give

747x-180y=5310(eq3)

600x-180y=8160(eq4)

see that y has the same value that is (-180y and +180y)

so to eliminate y completely you have to add eq1 and eq2 because if you don't add them together you wont eliminate y

747x-180y=5310

+

600x+180y=8160

=

1347x+0=13470

1347x=13470

x=13470/1347

x=10

Now to find y we use substitution method ie put x=10 in any of the equation above(eq1,eq2,eq3, eq4) you will get the same answer

eq1

83x-20y=590 where (x=10)

83(10)-20y =590

830-20y=590

like terms

-20y=590-830

-20y= -240

divide both sides with -20

y= -240/-20

y=12

OR

eq2

60x+18y=816 where x=10

60(10)+18y=816

600+18y=816

like term

18y=816-600

18y=216

y=216/18

y= 12

or eq3 or eq4 you will still get the same answer

8(-10x+3.5y-7)

8×-10x + 8×3.5y + 8×-7

-80x + 28y - 56

therefore

-80x+28y-56 is the correct answer

answer: the answer is (b) amie should have multiplied

step-by-step explanation: given a sphere and a cylinder with same radius and height.

let, 'r' be the radius of the cylinder and sphere and 'h' be the height of the cylinder. according to the question,

r = h.

now, the volume of the sphere will be

and the volume of the cylinder will be

therefore, we have

thus, ammie should have multiplied the volume of the sphere