x = number
If 7 times a number is subtracted from the square of the number the result is 30, means:
x² - 7 x = 30
Subtract 30 to both sides.
x² - 7 x - 30 = 0
The solutions are:
x = - 3 and x = 10
Check results.
For x = - 3
x² - 7 x = ( - 3 )² - 7 ( - 3 ) = 9 + 21 = 30
For x = 10
x² - 7 x = 10² - 7 ∙ 10 = 100 - 70 = 30
if 7 times a number is subtracted from the square of the number ,if the result is 30 .find the number
1 answer