Question

X2 +14x-15=0 in this equation which add LHS as a perfect square 49. how this 49 will come... please tell about 49??? how this calculated

Answer 1

x = 1, and x = - 15

Explanation:

`x^2 + 14x - 15 = 0`
`D = d^2 = b^2 - 4ac = 196 + 60 = 256` --> `d = +- 16`
There are 2 real roots:
`x = - b/(2a) +- d/(2a) = - 14/2 +- 16/2`
`x = - 7 +- 8`
a. x1 = - 7 + 8 = 1
b. x2 = -7 - 8 = - 15
Note.
Because a + b + c = 0, we use the shortcut.
One real root is x1 = 1, and the other is `x2 = c/a = - 15`.