How do you find the x and y intercepts for #y=x^2+6x-5#?

1 Answer
Mar 14, 2016

x-intercept --> #-3 +- sqrt14#

Explanation:

To find y-intercept, make x = 0 --> y = -5
To find x-intercepts, make y = 0 and solve the quadratic equation:
#y = x^2 + 6x - 5 = 0.#
#D = d^2 = b^2 - 4ac = 36 + 20 = 56 = 4*14# --> #d = +- 2sqrt14#
#x = - 6/2 +- (2sqrt14)/2 = -3 +- sqrt14#

NOTE
To simplify calculation, use the improved quadratic formula (Google, Yahoo Search) instead of the classical formula.
Improved formula
#D = d^2 = b^2 - 4ac#
#x = -b/(2a) +- d/(2a)#
Classical formula
#x = -b/(2a) +- (sqrt(b^2 - 4ac))/(2a)#