2007-10-30 01:02:38 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
2x + y = 5
5x +3y = 11
Take the first equation are rearrange it:
y = 5 - 2x
Now replace y in the second equation by (5 - 2x):
5x + 3(5 -2x) = 11
and simplify
5x + 15 - 6x = 11
4 - x = 0
So x = 4
y = 5 - 2x, so y = -3
final check
2x + y = 5 yup
5x + 3y = 11 yup
2007-10-30 01:14:00 · answer #1 · answered by Computer Guy 7 · 0⤊ 0⤋
when you say addition, do you mean elimination? cause elimination can be done by addition or subtraction.
addition:
get rid of one variable say x by multiplying both coefficients of x with a certain number to eliminate it.
-5(2x + y = 5)
2 (5x + 3y = 11)
distribute -5 to 2x + y = 5 and distribute 2 to 5x + 3y = 11.
we get:
-10x -5y = -25
10x + 6y = 22 then add the two equations:
-10x - 5y = -25
+ 10x + 6y = 22
= 0x + y = -3 notice that we do not have a value for x anymore so we get:
y= -3 -----> this is the value of y.
solving for x:
-3(2x + y = 5)
5x + 3y = 11 we get:
-6x - 3y = -15
+ 5x + 3y = 11
= -x + 0y = -4 no value for y anymore so,
-x = - 4 therefore; x = 4.
2007-10-30 08:34:19 · answer #2 · answered by gvlumbao 2 · 0⤊ 0⤋
OKay,im assuming the equations are 2x+y=5 and 5x+3y=11.
So, multiply 1st equation by -3, giving us -6x-3y=-15.
-x=-4, so x=4.
And (2*4)+y=5, so y=5-8=-3.
So, x=4, y=-3.
2007-10-30 08:23:57 · answer #3 · answered by yljacktt 5 · 0⤊ 0⤋
2x + y =5
2(2) + 1 = 5
5x + 3y=11
5 (1) + 3(2) =11
solve by adding
2 + 2+ 1= 5
5 + 2+2+2 = 11
2007-10-30 08:14:32 · answer #4 · answered by theresa b 2 · 0⤊ 0⤋
first write the question properly & legibly we can't say if it's
2x+y=55, x+3y=11 or
2x+y=5, 5x+3y=11
first clearly wrie this.
2007-10-30 08:15:21 · answer #5 · answered by venky 2 · 0⤊ 0⤋