Question

When 8 is subtracted from the square of a number, the result is 7times the number. Find the positive solution

Answer 1

x=8 , x=-1

Explanation:

let the number is x

According to the condition

`{x}^(2) - 8 = 7x \\ {x}^(2) - 7x - 8 = 0 \\ {x}^(2) - 8x + x - 8 = 0 \\ x(x - 8) + 1(x - 8) = 0 \\ (x - 8)(x + 1) = 0 \\ x - 8 = 0 \: or \: x + 1 = 0 \\ x = 8 \: or x = - 1`