Is (1,8) solution to the system of equations x+y=9, 2x+2y=18

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jess1999 | Student, Grade 9 | (Level 1) Valedictorian

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x  +  y = 9

2x+2y = 18

To check if (1,8) is a solution to this system, just plug the numbers into the equation

First let's check the first equation

1 + 8 = 9  add 1 and 8

By adding, you should get

9 = 9 since this equation is true we should check the second equation

2 ( 1 ) + 2 ( 8 ) = 18  multiply 2 with 1 and 2 with 8

By multiplying, you should get

2 + 16 = 18 add 2 with 16

By adding, you should get

18 = 18 this equation is true also

Since both of the equation were true, that means (1,8) is a solution to this set

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giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted on

We'll re-write the 2nd equation, dividing it by 2 both sides:

2x + 2y = 18 => x + y = 9

To verify if a pair of values represents the solution of a system, we need to substitute the values withind the equations of the system.

Therefore, we'll replace x and y by 1 and 8,within the 1st equation. We could replace the values within the 2nd equation, as well, since the 1st equation is equal to the 2nd one.

1 + 8 = 9

9 = 9

Since the equations are verified, then the pair of values (1 ; 8) represents the solution of the given system.

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