How do solve the following linear system?: $x + 2 y = 1, 9 x + 16 y = 3$ $x+2y=1 , 9 x+ 16y =3$ ?

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Answer 1 · 2016-02-09T06:41:04

$x = - 5$ $x=-5$ and $y = 3$ $y=3$

Let $x + 2 y = 1$ $x+2y=1$ the 1st equation
Let $9 x + 16 y = 3$ $9x+16y=3$ the 2nd equation

Use 1st into the 2nd equation

from 1st:
$x = 1 - 2 y$ $x=1-2y$

using 2nd:
$9 x + 16 y = 3$ $9x+16y=3$

$9 (1 - 2 y) + 16 y = 3$ $9(1-2y)+16y=3$

$9 - 18 y + 16 y = 3$ $9-18y+16y=3$

$- 2 y = - 6$ $-2y=-6$

$(cancel(-2)y)/cancel(-2)=(-6)/-2$

and $y=3$

Go back to the 1st equation and use $y=3$

$x=1-2y$
$x=1-2*3$
$x=1-6$
$x=-5$

have a nice day from the Philippines!

How do solve the following linear system?: x+2y=1 , 9 x+ 16y =3 x+2y=1,9x+16y=3 x+2y=1 , 9 x+ 16y =3 ?