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3 years ago

-2x+20y=-18 8x+10y=-18

Mathematics

1 answer:

erastovalidia [21]3 years ago

5 0

Answer:

x = -1

y = -1

Step-by-step explanation:

This is a system of equations- the set up of the problem lends well to using the elimination method. There are always many ways of solving a system of equations, both in methods and different strategies within each method. The problem isn't necessarily complete but I can assume you're being asked to solve for x and y values.

divide the first equation by -2. this means we can use elimination to cancel out the y value, and is also our simplest option (rather than multiplying the second equation by -2.

-2x + 20y = -18 --> x - 10y = 9

x - 10y = 9

8x + 10y = -18

Using the elimination method to essentially add the parts of the equations together, this comes out to 9x = -9 , meaning x = -1 .

We can then return to our original equations, and substitute -1 for x (either equation will work, but the second one is simpler and therefore the better option).

8 (-1) +10y = -18

-8 + 10y = -18

10y = -10

y = -1

CHECKING

Substitute both x and y values back into the original equations to check them. the sides should be equal if our values are correct.

-2 (-1) + 20 (-1) = -18

Our first equation works: 2 - 20 = -18

8 (-1) + 10 (-1) = -18

The second equation works as well: -8-10= -18

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Step-by-step explanation:

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3 years ago

5 yrs ago, Nuri was thrice as old as Sonu. 10 yrs later, Nuri will be twice as old Sonu. How old are Nuri n Sonu?

Papessa [141]

Answer:

Answer will be 50

Step-by-step explanation:

Let us suppose, present age of Nuri be ‘x’ years and present age of Sonu be ‘y’ years.

Now, it is given that five years ago, Nuri was thrice old as Sonu. Hence,

Five years ago,

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And relation between ages can be given as

Nuri’s age = 3×sonu’s age or

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So, ten years ago,

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And relation between ages can be written as

x+10 = 2(y+10)

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Now we can solve the equation (i) and (ii) to get values of x and ‘y’ or present ages of Nuri and Sonu.

Value of ‘x’ from equation (i) be

x = 3y-10 ……….(iii)

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3y-10-2y-10 = 0

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Answer:

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