System a:
−5x+3y=−8 (1) 3x−7y=−3 (2) Multiply equation (1) by 3 and equation (2) by 5:
3(−5x+3y)=3(−8) 5(3x−7y)=5(−3) −15x+9y=−24 (3) 15x−35y=−15 (4) Add equation (3) and equation (4):
(−15x+9y)+(15x−35y)=−24+(−15) −26y=−39 y=−26−39=23 Substitute y=23 into equation (1): −5x+3(23)=−8 −5x+29=−8 −5x=−8−29=−216−29=−225 x=−5−225=1025=25 System b:
−8x−2y=24 (1) 5x−3y=2 (2) Multiply equation (1) by -3 and equation (2) by -2:
−3(−8x−2y)=−3(24) −2(5x−3y)=−2(2) 24x+6y=−72 (3) −10x+6y=−4 (4) Subtract equation (4) from equation (3):
(24x+6y)−(−10x+6y)=−72−(−4) 24x+6y+10x−6y=−72+4 x=34−68=−2 Substitute x=−2 into equation (1): −8(−2)−2y=24 16−2y=24 −2y=24−16=8 y=−28=−4