Question

a+4b=9
2a+4b=16


pelo metodo de substituiçao PFV ME AJUDA PFVV

Answer 1

$a+4b=9~........~equacao~I\\2a+4b=16~......~equacao~II\\ \\Na~equacao~I:\\ \\a=9-4b\\ \\ Substitua~(a=9-4b)~na~equacao~II:\\ \\2a+4b=16\\ \\2(9-4b)+4b=16\\ \\18-8b+4b=16\\ \\-8b+4b=16-18\\ \\-4b=-2~(-1)\\ \\ 4b=2\\ \\ b=\frac{2}{4}\\ \\ b=\frac{1}{2} \\ \\ Substitua~(b=\frac{1}{2})~na~equacao~I:\\ \\a+4b=9\\ \\ a+4(\frac{1}{2})=9\\ \\ a+\frac{4}{2} =9\\ \\ a+2=9\\ \\ a=9-2\\ \\ a=7~~~~~~~~~~~~~~~~~~~~S=(a=7;~~b=\frac{1}{2})$