Question

Solve the following system.

4x^2 + 9y^2 = 72

x - y^2 = -1

Answer 1

\(\Large \color{MidnightBlue}{\Rightarrow -y^2 = -1 - x }\)
\(\Large \color{MidnightBlue}{\Rightarrow y^2 = 1 + x }\)

Solve it by substitution.

Answer 2

so,
x - y^2 = -1
or, y^2 = x+1
substitute this value of y^2 in the the first equation, and solve the quadratic in x hence obtained.