The system is:
i) <span>2x – 3y – 2z = 4
ii) </span><span>x + 3y + 2z = –7
</span>iii) <span>–4x – 4y – 2z = 10
the last equation can be simplified, by dividing by -2,
thus we have:
</span>i) 2x – 3y – 2z = 4
ii) x + 3y + 2z = –7
iii) 2x +2y +z = -5
The procedure to solve the system is as follows:
first use any pairs of 2 equations (for example i and ii, i and iii) and equalize them by using one of the variables:
i) 2x – 3y – 2z = 4
iii) 2x +2y +z = -5
2x can be written as 3y+2z+4 from the first equation, and -2y-z-5 from the third equation.
Equalize:
3y+2z+4=-2y-z-5, group common terms:
5y+3z=-9
similarly, using i and ii, eliminate x:
i) 2x – 3y – 2z = 4
ii) x + 3y + 2z = –7
multiply the second equation by 2:
i) 2x – 3y – 2z = 4
ii) 2x + 6y + 4z = –14
thus 2x=3y+2z+4 from i and 2x=-6y-4z-14 from ii:
3y+2z+4=-6y-4z-14
9y+6z=-18
So we get 2 equations with variables y and z:
a) 5y+3z=-9
b) 9y+6z=-18
now the aim of the method is clear: We eliminate one of the variables, creating a system of 2 linear equations with 2 variables, which we can solve by any of the standard methods.
Let's use elimination method, multiply the equation a by -2:
a) -10y-6z=18
b) 9y+6z=-18
------------------------ add the equations:
-10y+9y-6z+6z=18-18
-y=0
y=0,
thus :
9y+6z=-18
0+6z=-18
z=-3
Finally to find x, use any of the equations i, ii or iii:
<span>2x – 3y – 2z = 4
</span>
<span>2x – 3*0 – 2(-3) = 4
2x+6=4
2x=-2
x=-1
Solution: (x, y, z) = (-1, 0, -3 )
Remark: it is always a good attitude to check the answer, because often calculations mistakes can be made:
check by substituting x=-1, y=0, z=-3 in each of the 3 equations and see that for these numbers the equalities hold.</span>
Let the numbers be x and y
y=5x
y-x=236
5x-x=236
4x=236
x=59
5=5*59=295
Your answer is 160. Sorry about that answer above I laughed reading it hahaha.
Distributive property was the first property used in STEP 1, where -4 was distributed to -3x+ 2 resulting in the equation in STEP 1. Next in STEP 2, commutative property of addition no matter how 12x and 6x are arranged, when you add them together the result will be the same.
*Take note that 12x and 6x are put together because they are like terms.
For Steps 3 and 4, you will see that the addition property of equality was used in STEP 3. To keep the equation equal, you will add the same number on both sides.
STEP 4 uses Division property of Equality. Like Step 3, to keep both sides of the equation equal, you must divide both sides with the same number. It keeps the statement true by doing so.
STEP 4 and 5 uses transitive property if you examine both as a whole.
Transitive property assumes that if a = b and b = c, then a = c
If 18/18 (a) = 1 (b), and x (c) = 18/18(a) then, x (c) = 1 (b).
