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