How do you solve the system #4x-y=25# and #4x+5y=-29#?
2 Answers
use the elimination method to solve the simultaneous equations:
4x-y=25>eq no 1
4x+5y=-29>eq no 2
eq no 1-eq no 2
4x -y =25
(-4x-5y=29)the signs become opposite in the subtraction
0 -6y =54
-6y=54
y=54/-6
y=-9.
put the value of y=-9 into eq no 1.
(try to put the value in the equation with smaller values)
4x-(-9)=25
4x+9=25
4x=25-9
4x=16
x=16/4
x=4
S.S{4,-9}(remember that the value of the variable which comes first according to the alphabetic arrangement is always written first)
Explanation:
Solve by elimination and substitution
#color(blue)(4x-y=25#
#color(blue)(4x+5y=-29#
We could see that, we can eliminate
Subtract
Substitute the value of
#:.color(purple)({x,y}={-9,4}#