Thread: Weird inequalities?

A function is defined by . Find the value of the constant c for which the range of f is given by f(x)≥ 3

Originally Posted by Punch

A function is defined by . Find the value of the constant c for which the range of f is given by f(x)≥ 3

You could convert it to turning point form:



Then you can see that must equal , so must equal

So this is using the completing the square method

Originally Posted by Stroodle

You could convert it to turning point form:



Then you can see that must be , so must be

I have a question, the question states that, find the values of the constant c.

now we have an inequality so c can be anything more than 4, how do i answer the question? anything more than 4 or equals to 4 is right?

Originally Posted by Punch

I have a question, the question states that, find the values of the constant c.

now we have an inequality so c can be anything more than 4, how do i answer the question? anything more than 4 or equals to 4 is right?

The range is [3, +oo) if c = 4.

Originally Posted by mr fantastic

The range is [3, +oo) if c = 4.

Sorry but I didn't get you. If you don't understand my question, this was what i was asking, since c is found to be more than or equals to 4, what should i answer the question "find the value of the constant c"?

Sorry Punch, I made an error (I'll fix it now). As Mr Fantastic stated the answer is c=4.

Originally Posted by Punch

Sorry but I didn't get you. If you don't understand my question, this was what i was asking, since c is found to be more than or equals to 4, what should i answer the question "find the value of the constant c"?

The answer to the question you posted is c = 4, not . That is what my previous reply said. Stroodle made a small misunderstanding of the question: It is required that -1 + c = 3. This misunderstanding should have been clear to you given everything else said in that reply.