SOLUTION: When the sum of 5 and twice a positive number is subtracted from the square of the number 0 results. Find the number.

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Question 519391: When the sum of 5 and twice a positive number is subtracted from the square of the number 0 results. Find the number.
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
let the number be x
x^2-(2x+5)=0
x^2-2x-5=0
Find the roots of the equation by quadratic formula

a= 1 ,b= -2 ,c= -5

b^2-4ac= 4 + 20
b^2-4ac= 24
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29
x1=%28-12%2B21%29%2F%2812%29
x1=( 2 + 4.9 )/ 2
x1= 3.45
x2=( 2 -4.9 ) / 2
x2= -1.45
Ignore negative value
3.45 is the number
m.ananth@hotmail.ca