Question

3x+4y=7 4x-y=3 plz.
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Answer 1

Answer:

substitutions method :------

$3x + 4y = 7 \\ {eq}^{n} = (1)$

$4x - y = 3 \\ {eq}^{n} = (2)$

from equation ( 1 ) :------

$3x + 4y = 7 \\ 3x = 7 - 4y \\ x = \frac{7 - 4y}{3} \\ {eq}^{n} = (3)$

put the value of x in equation ( 2 ) :-------

$4x - y = 3 \\ 4( \frac{7 - 4y}{3} ) - y = 3 \\ 4(7 - 4y) - y = 3 \times 3 \\ 28 - 16y - y = 9 \\ - 17y = 9 - 28 \\ - 17 y= - 19 \\ y = \frac{19}{17}$

from equation ( 3 ) :--------------

$x = \frac{7 - 4y}{3} \\ x = \frac{7 - 4\frac{19}{17} }{3} \\ x = \frac{7 - 76}{3 \times 17} = \frac{69}{51} = \frac{23}{17} \\ x = \frac{23}{17}$

answer:-----------

x is 23/17 and y is 19/17