How do you Solve x2-5x-36 equals 0?

Answer 1

x2 - 5x - 36 = 0

(x - 9) (x + 4) = 0

x = 9 and x = -4

This method is called factoring and only works if the equation is a perfect square

otherwise you must use the quadratic equation. There are not enough mathematical symbols here to illustrate so you'll have to look it up. But you can determine if the equation is factorable using a part of the quadratic equation called the discriminate, if the discriminate is a perfect square the equation is factorable.

b2 - 4ac (discriminate)

Where a,b, and c are taken from the general form

ax2 + bx + c = 0

a = 1, b = -5, c = -36

If the square root of the discriminate is a whole number 3, 8, 122... the equation is factorable.

Notice above that 9 x -4 = -36 the c value and 9 + (- 4) = 5 the b value.

Start solving by listing all multiples of -36 and choose the two which when added give you 5.