Question

D) 2x+3y=9
4x - 5y = 7
Alguém me ajuda?​

Answer 1

$\begin{cases}\mathtt{2x+3y=9}\\\mathtt{4x-5y=7}\end{cases}$

multiplicando a 1ª equação por -2 temos

$+\underline{\begin{cases}\mathtt{-4x-6y=-18}\\\mathtt{4x-5y=7}\end{cases}}$

$\mathsf{-11y=-11}\\\mathsf{y=\dfrac{-11}{-11}}\\\large\boxed{\boxed{\boxed{\boxed{\mathsf{y=1}}}}}$

Substituindo o valor ds y na 1ª Equação temos:

$\mathsf{2x+3.1=9}\\\mathsf{2x+3=9}\\\mathsf{2x=9-3}\\\mathsf{2x=6}\\\mathsf{x=\dfrac{6}{2}}\\\large\boxed{\boxed{\boxed{\boxed{\mathsf{x=3}}}}}$

$\huge\boxed{\boxed{\boxed{\boxed{\mathsf{s=\{3,1\}}}}}}$