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When using the quadratic formula to solve a quadratic equation.........?
(ax^2 + bx + c = 0), the discriminant is b^2 - 4ac. This discriminant can be positive, zero, or negative.
Create three unique equations where the discriminant is positive, zero, or negative. For each case, explain what this value means to the graph of y = ax^2 + bx + c.
HELP ME!!!!!!
7 Answers
- Anonymous2 decades agoFavorite Answer
Positive discriminant
(x-a)(x-b) is and eqn where both a and b can be any real nos. eg (x-3)(x-4) simplify = x^2 -7x +12
(x-2/3)(x-7/5) simplify
(in fact general form (ax+b)(cx +d) where a,b,c,d are real.)
2. (ax+b)^2 =0 has equal roots i.e d=0
(2x +3)^2 = 0 solve to get eqn 4x^2 +12x +9 =0
3. if you know complex then (x +a)(x+b)= 0 has d -ive if a,b are complex or imaginary
otherwise x^ 2= -ive no will also have d <0
eg X^2 +9 =0 or (x+3i)(x-3i)=0
on graph the parabola cuts x axis at two point d>0
one point the turning point d= 0
no point d <0
- Henry LLv 42 decades ago
To make the discriminant what you want just pick out your (b) well.
For instance... a=1; b=10; c=1... the discriminant is: 96 (positive)
For instance... a=1; b=1; c=1... the discriminant is: -3 (negative)
For instance... a=1; b=2; c=1... the discriminant is: 0 (zero)
When the discriminant is:
positive... the graph has (2) real zeros.
negative... the graph has (2) imaginary zeros.
zero... the graph has (1) real zero.
English...
Zeros are where the graph crosses the x-axis. If a graph crosses the x-axis twice, it has two zeros. If the graph touches the x-axis once (x^2 for example), it has one zero. If the graph has imaginary zeros, then the graph doesn't cross at all. Meaning the graph is always above the x-axis.
- haribLv 45 years ago
nicely the formula for fixing an quadratic equation is -b + - the sq. root of b squared + 4 x A rewrite the equation like this 8x + x -5 8x=A x=b and -5 is c -x + and minus x to the 2d skill + 4 x 8 x -5 be squared equals 8x8 that's sixty 4 + 4 x a x -5 an excellent 20 x X 20 x a million is 20 the sq. root of 20 is 4.40 seven + -8 = -3.fifty 3 then minus is is 11.fifty 3 so that you've 2 solutions 11.fifty 3 effective and -3.fifty 3 unfavorable volume thats how i do quadratic equations I dont understand if its top you would opt to envision with someone who's familiar with more desirable about the stuff like a math instructor
- 2 decades ago
if b^2 - 4ac = 0, it means that there is exactly one solution.
if you graph y = ax^2 + bx + c, it is a parabola. the vertex of that parabola will touch exactly one point (the solution) on the x-axis.
if b^2 - 4ac = a positive number, it means that there are two solutions. if you graph the parabola, the vertex will be below the x-axis, which means that the parabola will cross two points (2 solutions) on the x-axis
if b^2 - 4ac = negative, the vertex of the parabola will be above the x-axis. this means that no points touch the x-axis, so therefore there is no real solution. also, for this case, if b^2 - 4ac is negative, the quadratic equation takes the square root of if b^2 - 4ac. you can not take the square root of a negative number, that is also why there is no real solutions, just imaginary
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- Anonymous2 decades ago
well for the one where the discriminant is zero, couldnt you just make a, b, and c all equal zero? or is that like cheating? for the negative one, you could do like (3)^2 -4(4)(5), so that would be 4x^2 + 3x + 5 = 0. For the positive one you could do (6)^2 -4(4)(2), so that would be 4x^2 + 6x + 2 = 0. Hope thats what you were looking for!
- 2 decades ago
The quadratic formula is ... : X equals the opposite of B plus/minus the square root of B squared minus 4AC, all over 2A. A = The whole number; B= The variable amount; C= The variable squared amount.
It's really hard to explain, because I don't know how to type the symbols on my computer... sorry...
- 2 decades ago
wow....sucks for you, im done with all this algebra crap for the summer. good luck with this one