Hello, Could you help me with these two inequalities? , all of them taken of Precalculus Stewart Book, Chapter 1, Exercise 1.7.

The first is:

-2x^2 ≤ 4

The answer must be (-∞, ∞)

but I got as last result x^2 ≥ -2

and it can't be root of 2, because it would be a complex number, can I?

I can't either factorize or something else.

The second is 2/5 x + 1< 1/5 -2x

and this book only have solutions for odd numbers, this is number sixteen, I got:

10/5 x + 1 < 1-2x

x +1 < 1-2/2 x

x < 1/2

I did it wrong?

Ah I forgot it... I have doubts of when change the sign 'greater than' for 'less than"

Still confused about that.

Thanks :)