Solve the system of equations using multiplication. 3x + 8y = –20 5x – y = –19

[tex]3x + 8y = -20[tex]

[tex]5x - y = -19[tex]

[tex]3x + 8y = -20[tex]

[tex]40x - 8y = -152[tex] (multiply both sides by 8)

Add the two equations together.

[tex](3x + 8y) + (40x - 8y) = -20 + (-152)[tex]

Which makes it

[tex]43x = -172[tex]

Then divide 43 by both sides.

[tex]x = -4[tex]

Then get [tex]y[tex] by substituting [tex]x[tex]

[tex]5 * (-4) - y = -19[tex]

And solve the equation.

[tex]5 * (-4) - y = -19[tex]

[tex]5 * (-4) - (-19) = y[tex]

[tex]-20 + 19 = y[tex]

[tex]y = -1[tex]

So the answer is:

[tex]x = -4 , y = -1[tex]

geometry: triangles

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lessons

answers archive

call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

25.45584

e^-kt = n/n0 = 0.79  

-kt = ln 0.79  

t = - ln 0.79/0.0001  

= 2357 years

step-by-step explanation: