Question

The square of a number is two times the number plus 7

Answer 1

Explanation:

Let the number = x

x^2 = 2*x + 7 Subtract 2x + 7 from both sides

x^2 - 2x - 7 = 0

a = 1

b = -2

c = - 7

x = (-b +/- sqrt(b^2 - 4ac))/2a General Formula

x = (-(-2) +/- sqrt((-2)^2 - 4*1*(-7))/2 Values substituted

x = (2 +/- sqrt(4 + 28))/2 Combine the square root

x = (2 +/- sqrt(32))/2 sqrt(32) = sqrt(4*4*2) = 4sqrt(2)

x = (2 +/- 4sqrt(2)) /2 Divide by 2

x = 1 + 2*sqrt(2)