How do you solve the following linear system: $- 7 x - 5 y = 4, - x + y = 21$ $-7x - 5y =4, -x + y = 21$ ?

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How do you solve the following linear system: $- 7 x - 5 y = 4, - x + y = 21$ $-7x - 5y =4, -x + y = 21$ ?

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Answer 1 · 2015-11-14T22:00:01

$x = \frac{101}{12}$ $x = 101/12$ ,

$y = \frac{353}{12}$ $y = 353/12$ .

Explanation:

We start with:
$- 7 x - 5 y = 4$ $- 7x - 5y = 4$ ,
$- x + y = 21$ $- x + y = 21$ .

There are three ways of solving these problems. I'll choose substitution, as I find it easier. Let's start. First of all, we leave $x$ $x$ or $y$ $y$ alone in any of the $2$ $2$ equations. So,
$- x + y = 21$ $-x + y = 21$ ,
$y = x + 21$ $y = x + 21$ .

We now substitute this into the other equation:
$- 7 x - 5 (x + 21) = 4$ $- 7x - 5(x + 21) = 4$ ,
$- 7 x - 5 x + 105 = 4$ $- 7x -5x + 105 = 4$ ,
$- 12 x = - 101$ $- 12x = -101$ , Which we can write as:
$12 x = 101$ $12x = 101$
$x = \frac{101}{12}$ $x = 101/12$ .

We now substitute this into any of the equation. I'll choose the second one:

$- \frac{101}{12} + y = 21$ $- 101/12 + y = 21$ ,
$y = 21 + \frac{101}{12}$ $y = 21 + 101/12$
$y = \frac{353}{12}$ $y = 353/12$ .

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How do you solve the following linear system: $- 7 x - 5 y = 4, - x + y = 21$ $-7x - 5y =4, -x + y = 21$ ?

1 Answer

Explanation:

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Science

Math

Humanities

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How do you solve the following linear system: −7x−5y=4,−x+y=21-7x - 5y =4, -x + y = 21 ?

1 Answer

Explanation:

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Impact of this question

How do you solve the following linear system: $- 7 x - 5 y = 4, - x + y = 21$ $-7x - 5y =4, -x + y = 21$ ?