How do you solve the following linear system: -9 y + 2x = 2 , 5x - y = 39y+2x=2,5xy=3?

2 Answers
May 30, 2017

See a solution process below:

Explanation:

Step 1) Solve the second equation for yy:

5x - y = 35xy=3

-color(red)(3) + 5x - y + color(blue)(y) = -color(red)(3) + 3 + color(blue)(y)3+5xy+y=3+3+y

-3 + 5x - 0 = 0 + color(blue)(y)3+5x0=0+y

-3 + 5x = y3+5x=y

y = -3 + 5xy=3+5x

Step 2) Substitute (-3 + 5x)(3+5x) for yy in the first equation and solve for xx:

-9y + 2x = 29y+2x=2 becomes:

-9(-3 + 5x) + 2x = 29(3+5x)+2x=2

(-9 xx -3) + (-9 xx 5x) + 2x = 2(9×3)+(9×5x)+2x=2

27 - 45x + 2x = 22745x+2x=2

27 + (-45 + 2)x = 227+(45+2)x=2

27 - 43x = 22743x=2

-color(red)(27) + 27 - 43x = -color(red)(27) + 227+2743x=27+2

0 - 43x = -25043x=25

-43x = -2543x=25

(-43x)/color(red)(-43) = (-25)/color(red)(-43)43x43=2543

(color(red)(cancel(color(black)(-43)))x)/cancel(color(red)(-43)) = 25/43

x = 25/43

Step 3) Substitute 25/43 for x in the solution to the second equation at the end of Step 1 and calculate y:

y = -3 + 5x becomes:

y = -3 + (5 xx 25/43)

y = -3 + 125/43

y = (-3 xx 43/43) + 125/43

y = -129/43 + 125/43

y = -4/43

The solution is: x = 25/43 and y = -4/43 or (25/43, -4/43)

May 30, 2017

x=25/43, y=-4/43.

Explanation:

From the second eqn., 5x-3=y.

Subst.ing this value of y in the first eqn., we get,

-9(5x-3)+2x=2.

:. -45x+27+2x=2.

:. -43x=2-27=-25.

:. x=25/43.

:. y=5x-3=5(25/43)-3=125/43-3=(125-129)/43.

;. y=-4/43.

Hence, the Soln. x=25/43, y=-4/43.