What is x if x squared plus x equals 15?

Answer 1

X2 + X = 15

X2 + X - 15 = 0

Looks like a job for the quadratic formula. ( the discriminant says two real roots )

X = - b (+/-) sqrt(b2- 4ac)/2a

a = 1

b = 1

c = - 15

X = - 1 (+/-) sqrt[12 - 4(1)(- 15)]/2(1)

X = - 1 (+/-) sqrt(1 + 60)/2

X =[ - 1 (+/-) sqrt(61)]/2

---------------------------------exact answer

So, X = ~ 3.41

X = ~ - 4.41