C1 help !!!!!!!!!!

Q. Find the set of values of x for which:

4x^2 - 3x - 1 < 0 and 4(x+20) < 15 - (x + 7)

Cant seem to factorise the quadratic

In usual fashion you want to find two numbers that add to make -3 and multiply to make -4.

(4X+1)(X-1)

Whoh.
The way i factorise is different i will put (4x ) (4x )
Find two numbers multiplyto give -3 add to give -1 i'm confused as to which two numbers??

Whoh.
The way i factorise is different i will put (4x ) (4x )
Find two numbers multiplyto give -3 add to give -1 i'm confused as to which two numbers??

You don't put 4x at the beginning of both. Think about what happens when you expand it; you'll get 16x^2.

That's how i factorise quadratics when coefficient is greater than 1.
Why is it with this question i can't?

Well assuming you mean like (4x + ?)(4x + ?) that wouldn't work here..
multiply to make -4. You generally just want to exhaust the factors, positive and negative of the number AC in Ax^2 + Bx + C, until you find the two that also add to make B. Then you write out the x-term as the sum of two x terms whose coefficients are the two numbers and this allows you to factorize. Eventually you'll probably be able to factorize expressions like this very quickly just by experience/recognition

So answer is (4x-4) (x+1)

No. Note that 4x^2 - 3x - 1 = 4x^2 - 4x + x - 1. can you see how to factorize this?