4x + y = -5
4x +3y =9
2007-09-28 02:57:46 · 5 answers · asked by nickmydog 1 in Science & Mathematics ➔ Mathematics
4x + y = -5
4x + 3y = 9
Choose a equation
4x + y = -5
4x = -5 - y
x = -5/4 - y/4
sub it into the other equation
4x +3y = 9
4(-5/4 - y/4) + 3y = 9
-20/4 - 4y/4 + 3y = 9
-5 - y + 3y = 9
-5 + 2y = 9
2y = 14
y = 7
sub the y into the origanial equation you first used
4x + y = -5
4x + 7 = -5
4x = -12
x = -3
x = -3
y = 7
2007-09-28 03:08:42 · answer #1 · answered by Brad K 2 · 0⤊ 0⤋
1. 4x+y=-5
4x+3y=9
2. 4x+y= -5 (subtract the 2nd equation from the 1st equation)
-
4x+3Y=9
3. -2y= -14 (after subtracting, get the value of y)
y=7
4. 4x+3(7)=9
4x+21=9
4x=9-21 ------> 4x= -12
x= -3
(after getting the value of y, substitue with either the first of second equation. in this case, i substituted it with the second) (by the way, i used the elimination method. it's a method wherein you first need to eliminate one of the variables in order to solve the linear system)
2007-09-28 03:11:50 · answer #2 · answered by Anonymous · 0⤊ 0⤋
subtract equation 1 from eqn. 2:
2y = 14
y = 7
Plug in this value into eqn. 1:
4x + 7 = -5
4x = -12
x = -3
2007-09-28 03:03:55 · answer #3 · answered by jamaliekal 2 · 1⤊ 0⤋
let, 2x-3y = 4 be equation -1 and let, 8x +3y = 1 be equation -2. taking eq 1 -> 2x = 4 +3y -> x = 4+3y/2 (equation 3) now taking eq 2 and substituting the value of x in eq 3 -> i.e., -> 8(4+3y/2) + 3y = 1 32 + 24y /2 +3y = 1 32 +24 y + 6y /2 = 1(taking l.c.m) 32 + 30y = 2(by cross multiplication) 30y = 32 - 2 30 y = 30 y = 30/30 y = 1 (equation 4) now, putting the value of y of eq - 4 in eq - 3) x = 4+3y/2 x = 4 + (3*1)/2 x = 4+3/2 x = 7/2 Therefore, x = 7/2 & y = 1 -> ans
2016-05-20 22:53:59 · answer #4 · answered by ? 3 · 0⤊ 0⤋
- 4x - y = 5
4x + 3y = 9-----ADD
2y = 14
y = 7
4x + 7 = - 5
4x = - 12
x = - 3
x = - 3 , y = 7
2007-09-28 07:09:45 · answer #5 · answered by Como 7 · 0⤊ 0⤋