How do you find the x and y intercept of $7x + 3y = –21$ ?

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Answer 1 · 2017-02-25T13:32:29

See the entire solution process below:

To find the $x$ intercept by substitution you substitute $0$ for $y$ and solve for $x$ :

$7x + 3y = -21$ becomes:

$7x + (3 xx 0) = -21$

$7x + 0 = -21$

$7x = -21$

$(7x)/color(red)(7) = -21/color(red)(7)$

$(color(red)(cancel(color(black)(7)))x)/cancel(color(red)(7)) = -3$

$x = -3$ so the x-intercept is $-3$ or $(-3, 0)$

To find the $y$ intercept by substitution you substitute $0$ for $x$ and solve for $y$ :

$7x + 3y = -21$ becomes:

$(7 xx 0) + 3y = -21$

$0 + 3y = -21$

$3y = -21$

$(3y)/color(red)(3) = -21/color(red)(3)$

$(color(red)(cancel(color(black)(3)))y)/cancel(color(red)(3)) = -7$

$y = -7$ so the y-intercept is $-7$ or $(0, -7)$

How do you find the x and y intercept of 7x + 3y = –217x + 3y = –21?