Question

Qual é o valor de x e y ?


7x+4y= 28

8y+2x= 14

Answer 1

7x+4y=28
7x=28/4y
x=28/4y+7

7 (28/4y+7)+4y=28
196/28y+49+4y=28
196+4y =28*28y+49
196+4y=784y+1372
4y=784y+1372-196
4y-784y=1176
-780y=1176
y=1176/-780 : 2 =588/-390 :2 294/-195
y=294/-195 ou - 1,507

7x+4 (294/-195)=28
7x+1176/-780=28
7x+1176=28*-780
7x+1176=-21840
7x=-21840-1176
7x=-23016
x=-23916/7
x=-3288
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8y+2x=14
8y=14/2x
y=14/2x+8

8(14/2x+8)+2x=14
112/16x+64+2x=14
112+2x=14*16x+64
112+2x=224x+896
2x=224x+896-112
2x-224x=784
-222x=784
x=784/-222 :2 = 392/-111
x=392/-111 ou -3,53

8y+2(392/-111)=14
8y+784/-222=14
8y+784=14*-222
8y+784=-3108
8y=3108-784
8y=2324
y=2324/8 :4= 581/2
y=581/2 ou 290,5