How do solve the following linear system?: $3 x + y = 20, - 3 x - 8 y = - 9$ $3x + y =20 , -3x -8y = -9$ ?

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How do solve the following linear system?: $3 x + y = 20, - 3 x - 8 y = - 9$ $3x + y =20 , -3x -8y = -9$ ?

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Answer 1 · 2016-03-09T23:29:24

$x = (\frac{151}{21})$ $x=(151/21)$ and $y = (- \frac{11}{7})$ $y=(-11/7)$ or in other words the solution is the ordered pair $(\frac{151}{21}, - \frac{11}{7})$ $(151/21,-11/7)$

Explanation:

We will use the "Elimination Method" to help us start to solve this problem. I can easily eliminate the $x$ $x$ variable by addind the two equations:
$3 x + y = 20$ $3x+y =20$
$- 3 x - 8 y = - 9$ $-3x-8y=-9$ by adding like terms we get:

$- 7 y = 11$ $-7y =11$
$y = - \frac{11}{7}$ $y =-11/7$
Now that I have a value for $y$ $y$ , I will substitute that in the first equation and solve for $x$ $x$
$3 x + y = 20$ $3x+y=20$
$3 x + (- \frac{11}{7}) = 20$ $3x +(-11/7) = 20$
$3 x = 20 + \frac{11}{7}$ $3x = 20+11/7$ I need a common denominator, which is $7$ $7$
$3 x = \frac{140}{7} + \frac{11}{7}$ $3x = 140/7 + 11/7$
$3 x = \frac{151}{7}$ $3x=151/7$ Divide both sides of the equation by $3$ $3$
$x = \frac{151}{21}$ $x=151/21$

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How do solve the following linear system?: $3 x + y = 20, - 3 x - 8 y = - 9$ $3x + y =20 , -3x -8y = -9$ ?

1 Answer

Explanation:

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Science

Math

Humanities

... and beyond

How do solve the following linear system?: 3x+y=20,−3x−8y=−9 3x + y =20 , -3x -8y = -9 ?

1 Answer

Explanation:

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How do solve the following linear system?: $3 x + y = 20, - 3 x - 8 y = - 9$ $3x + y =20 , -3x -8y = -9$ ?