How do you find the x and y intercepts for y=x^2+6x-5y=x2+6x−5?

1 Answer
Nghi N.
Mar 14, 2016

x-intercept --> -3 +- sqrt14−3±√14

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.y=x2+6x−5=0.
D = d^2 = b^2 - 4ac = 36 + 20 = 56 = 4*14D=d2=b2−4ac=36+20=56=4⋅14 --> d = +- 2sqrt14d=±2√14
x = - 6/2 +- (2sqrt14)/2 = -3 +- sqrt14x=−62±2√142=−3±√14

NOTE
To simplify calculation, use the improved quadratic formula (Google, Yahoo Search) instead of the classical formula.
Improved formula
D = d^2 = b^2 - 4acD=d2=b2−4ac
x = -b/(2a) +- d/(2a)x=−b2a±d2a
Classical formula
x = -b/(2a) +- (sqrt(b^2 - 4ac))/(2a)x=−b2a±√b2−4ac2a

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