Math Help - Can you... Prove that

1. Can you... Prove that

Hello all, wondering if you could give me a hand,

Prove that the equation 4=x(2-x) has no real roots.

Max

2. Expand, move everything to one side, so that you have a quadratic of the form $ax^2 + bx + c = 0$.

Then check the discriminant. If the discriminant is negative, then there are not any real roots.

3. Thanks a lot, I get it now.

Max

4. Originally Posted by Max888
Hello all, wondering if you could give me a hand,

Prove that the equation 4=x(2-x) has no real roots.

Max
Alternatively, here's how Fred Flinstone might have done it...

$4=x(2-x)$

$x(x-2)=-4$

$(a\ number)(a\ value\ 2\ less\ than\ that\ number)=-4$

$1(-1)=-1$

To get a $-4,$ we need a $+4$ instead of 1

or a $-4$ instead of $-1$

Apart from those, we need $(2)(-2)$ or $(-3.?)(1.?)$

or $(-1.?)(3.?)$

or $(4.?)(-0.?)$ etc, etc none of which can differ by 2

Much quicker to know the "abc" formula.

5. Right, thanks a lot!