Question 1087718
5x-6y+4z=15
7x+4y-3z=19
2x+y+6z=46
<pre>5x - 6y + 4z = 15 ------ eq (i)
7x + 4y - 3z = 19 ----- eq (ii)
2x + y + 6z = 46 ------ eq (iii)
12x + 6y + 36z = 276 ---------- Multiplying eq (iii) by 6 -------- eq (iv)
17x + 40z = 291 --------------- Adding eqs (iv) and (i) ---------- eq (v)
- 8x - 4y - 24z = - 184 ------- Multiplying eq (iii) by - 4 ------ eq (vi)
- x - 27z = - 165 ------------- Adding eqs (vi) and (ii) --------- eq (vii)
- 17x - 459z = - 2,805 -------- Multiplying eq (vii) by 17 ------- eq (viii)
- 419z = - 2,514 -------------- Adding eqs (viii) & (v)
{{{highlight_green(matrix(1,5, z, "=", "- 2,514"/(- 419), "=", 6))}}}


- x - 27(6) = - 165 ----------- Substituting 6 for z in eq (vii)
- x - 162 = - 165
- x = - 165 + 162
- x = - 3
{{{highlight_green(matrix(1,5, x, "=", (- 3)/(- 1), "=", 3))}}}


2(3) + y + 6(6) = 46 ---------- Substituting 3 for x, and 6 for z in eq (iii)
6 + y + 36 = 46
42 + y = 46
y = 46 - 42
{{{highlight_green(matrix(1,3, y, "=", 4))}}}
I wonder who besides the other person who responded, would do the problem the way he did.
Who solves a system like this, by substitution, with all those MESSY, MESSY fractions? Get with it, and help the people the right way!
I get confused just looking at the way he did the problem! I'm sure others feel the same way!</pre>