Question

What should be added to x^2 + 4 to get 2x^2 + 5

Answer 1

$\huge{\mathcal{\blue{\underline{Answer}}}}$

Let the number which should be added be "Z"

$x {}^{2} + 4 + z = 2x {}^{2} + 5 \\ z = 2x {}^{2} - x {}^{2} + 5 - 4 \\ z = x {}^{2} + 1$

hence The number

$x {}^{2} + 1$

Should be added to

$x {}^{2} + 4$

To get

$2x {}^{2} + 5$