As shown in the figure, if it is y = x 2+1, then obviously, if both the y axis and y are greater than 1, the value range is1,+infinity).

Solution of inequality

It is the content of junior high school. You can think of inequality as an equation.

It should be noted that 1/ If both sides are multiplied by or divided by a positive number at the same time, the sign direction remains unchanged.

2/ If both sides are multiplied or divided by a negative number at the same time, then the change of sign direction is ok?

Parity of judgment function

That is, you choose two values, one is X and the other is its opposite number-X brings both numbers into f(x).

If f(x)=f(-x) is an even function,

If -f(x)=f(-x) is odd function.

Power function is clearly defined in the book.

Zero is easier to understand. Zero is when the function value is 0, that is, f(x)=0.

To judge whether there is a zero point in an interval A and B, just calculate f(a) and f(b).

If f (a) × f (b)

draw

Another case is that the function image is just tangent to the X axis, then

You need another way.