Science

Math

Humanities

... and beyond

Socratic Meta
Featured Answers

Topics

How do you solve the system -3(5+x)=y and 5(x-3)=2y+4?

1 Answer

Jul 7, 2015

$(x, y) = (- 1, - 12)$ $(x,y) = (-1,-12)$

Explanation:

Given:
[1] $XXXX$ $color(white)("XXXX")$ $- 3 (5 + x) = y$ $-3(5+x)=y$
[2] $XXXX$ $color(white)("XXXX")$ $5 (x - 3) = 2 y + 4$ $5(x-3)=2y+4$

Replace $y$ $y$ in [2] with $- 3 (5 + x)$ $-3(5+x)$ as specified in [1]
[3] $XXXX$ $color(white)("XXXX")$ $5 (x - 3) = 2 (- 3 (5 + x)) + 4$ $5(x-3)=2(-3(5+x))+4$

Simplifying
[4] $XXXX$ $color(white)("XXXX")$ $5 x - 15 = - 30 - 6 x + 4$ $5x-15 = -30-6x+4$
[5] $XXXX$ $color(white)("XXXX")$ $11 x = - 11$ $11x = -11$
[6] $XXXX$ $color(white)("XXXX")$ $x = - 1$ $x = -1$

Substituting $x = - 1$ $x=-1$ back in [1]
[7] $XXXX$ $color(white)("XXXX")$ $- 3 (5 - 1) = y$ $-3(5-1) = y$
[8] $XXXX$ $color(white)("XXXX")$ $y = - 12$ $y = -12$

Related questions

See all questions in Linear Systems with Multiplication

Impact of this question

1425 views around the world

You can reuse this answer
Creative Commons License