1. ## Finding value of c in a quadratic

The remainder when -4x^2 + 2x + 7 is divided by (x - c) is -5. Find a possible whole number value of c.

This is what I tried to do:

P(c)= -4c^2 + 2c + 7
-4c^2 + 2c + 7 = -5
-4c^2 + 2c = -12

Is this right? If so, what do I do next?

2. $c(-2c+1)=-6\rightarrow c=\pm 1, \pm 2, \pm 3, \pm 6$ and you should check that $1-2c$ is correct... But if you solve the quadratic you can see that there are so real solutions for $c$...

3. Sorry...I don't understand.

4. Sorry, it's my fault I were wrong. Just solve it as a quadratic equation: $-4c^2 + 2c = -12\Rightarrow -2c^2+c+6=0\rightarrow c_{1,2}=\frac {-1\pm\sqrt{1^2-4\cdot (-2)\cdot 6}}{-4}=$ $\frac {-1\pm 7}{-4}\rightarrow c_1=2\quad c_2=-\frac 32$
Only 2 is a whole number. Try it: $-4x^2 + 2x + 7=(x-2)(-4x-6)-5$. Yeah