Science

Math

Humanities

... and beyond

Socratic Meta
Featured Answers

Topics

How do solve the following linear system?: $x + y = 2, y = 4 x + 4$ $x + y = 2, y = 4x + 4$ ?

1 Answer

Jan 25, 2016

You could use the "Substitution Method" to get
$XXX (x, y) = (- \frac{2}{5}, \frac{12}{5})$ $color(white)("XXX")(x,y)=(-2/5,12/5)$

Explanation:

Given:
[1] $XXX x + y = 2$ $color(white)("XXX")x+y=2$
[2] $XXX y = 4 x + 4$ $color(white)("XXX")y=4x+4$

Substitute $4 x + 4$ $4x+4$ for $y$ $y$ (from equation [2]) in equation [1]
[3] $XXX x + 4 x + 4 = 2$ $color(white)("XXX")x+4x+4=2$

Simplify equation [3]
[4] $XXX 5 x = - 2$ $color(white)("XXX")5x=-2$

[5] $XXX x = - \frac{2}{5}$ $color(white)("XXX")x=-2/5$

Substitute $(- \frac{2}{5})$ $(-2/5)$ for $x$ $x$ (from equation [5]) in equation [1]
[6] $XXX (- \frac{2}{5}) + y = 2$ $color(white)("XXX")(-2/5)+y=2$

Simplify
[7] $XXX y = \frac{12}{5}$ $color(white)("XXX")y=12/5$

Related questions

See all questions in Systems Using Substitution

Impact of this question

1228 views around the world

You can reuse this answer
Creative Commons License