How do you solve the following system?: $- 21 x + 3 y = 21, - 6 x + 3 y = 17$ $-21x+3y=21 , -6x+3y=17$

Question

How do you solve the following system?: $- 21 x + 3 y = 21, - 6 x + 3 y = 17$ $-21x+3y=21 , -6x+3y=17$

1 Answer

Impact of this question

1337 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-11-29T00:40:30

$(- \frac{4}{15}, \frac{77}{15})$ $(-4/15 , 77/15)$

Explanation:

Given system of equation
$- 21 x + 3 y = 21 (1)$ $-21x+3y= 21 " " " " " " (1)$
$- 6 x + 3 y = 17 (2)$ $-6x+3y =17 " " " " " " (2)$

Multiply the first equation by $- 1$ $-1$

$- 1 \cdot (- 21 x + 3 y = 21)$ $-1 * (-21x+3y=21)$

$21 x - 3 y = - 21 (3)$ $21x-3y=-21 " " " (3)$

Add equation $(2)$ $(2)$ from equation $(3)$ $(3)$

$21 x - 3 y = - 21$ $21x-3y=-21$
$- 6 x + 3 y = 17$ $-6x+3y=17$
$--------------------------------$ $stackrel("--------------------------------")$

$15 x = - 4$ $15x = -4$

$x = - \frac{4}{15}$ $color(red)(x =- 4/15)$

Substitute $x = - \frac{4}{15}$ $x=-4/15$ for $y$ $y$ in equation $(1)$ $(1)$

$- 21 \cdot (- \frac{4}{15}) + 3 y = 21$ $-21*(-4/15) + 3y= 21$

$\frac{28}{5} + 3 y = 21$ $28/5 +3y =21$

$5 (\frac{28}{5} + 3 y = 21)$ $5(28/5+3y=21)$

$28 + 15 y = 105$ $28+15y =105$

$15 y = 77$ $15y= 77$

$y = \frac{77}{15}$ $color(red)(y = 77/15)$

Science

Math

Humanities

... and beyond

How do you solve the following system?: $- 21 x + 3 y = 21, - 6 x + 3 y = 17$ $-21x+3y=21 , -6x+3y=17$

1 Answer

Explanation:

Related questions

Impact of this question

Science

Math

Humanities

... and beyond

How do you solve the following system?: −21x+3y=21,−6x+3y=17-21x+3y=21 , -6x+3y=17

1 Answer

Explanation:

Related questions

Impact of this question

How do you solve the following system?: $- 21 x + 3 y = 21, - 6 x + 3 y = 17$ $-21x+3y=21 , -6x+3y=17$