Quadratic equation & Minus B

How do I solve the quadratic equation ax^2+bx+c=0 using the minus b formula, x=-b+- sqrt b^2-4ac/2a on MATLAB

Thank you

[Geoff Hayes]

Fergal - are a, b, and c known? If so, wouldn't the code just be

x1 = (-b + sqrt(b^2 - (4 * a * c))) / (2 * a);
x2 = (-b - sqrt(b^2 - (4 * a * c))) / (2 * a);

assuming a is not zero...

[Fergal Ahern]

Geoff - The program must read in coefficients a,b and c from the keyboard and then calculate the roots of the equation. Do you know how I would verify that real roots are generated?

[James Tursa]

To read coefficients from the keyboard, you could use the input function

https://www.mathworks.com/help/matlab/ref/input.html?searchHighlight=input&s_tid=doc_srchtitle

To see if a number is real, you could use the isreal function

https://www.mathworks.com/help/matlab/ref/isreal.html?searchHighlight=isreal&s_tid=doc_srchtitle

Answer 1

[kirti singh]

The following example code snippet works for accepting the coefficients a,b and c and calculating the roots and finding if they are real or not:

a1 = 'Enter value of a ';
a = input(a1)
b1= 'Enter value of b ';
b = input(b1)
c1= 'Enter value of c ';
c = input(c1)
x1 = (-b + sqrt(b^2 - (4 * a * c))) / (2 * a);
x2 = (-b - sqrt(b^2 - (4 * a * c))) / (2 * a);
t1=isreal(x1);
t2=isreal(x2);

[James Tursa]

Please don't post complete solutions to homework problems.

Answer 2

[Pavi thra]

a1 = 'Enter value of a ';

a = input(a1)

b1= 'Enter value of b ';

b = input(b1)

c1= 'Enter value of c ';

c = input(c1)

x1 = (-b + sqrt(b^2 - (4 * a * c))) / (2 * a);

x2 = (-b - sqrt(b^2 - (4 * a * c))) / (2 * a);

t1=isreal(x1);

t2=isreal(x2);