✔ 最佳答案
The quadradic formula is:
x = [ -b ± √(b² - 4ac)] / (2a)
You have to get the formula into the following format for it to work:
ax² + bx + c = 0
So first, get it in the format:
x² - 7x - 1 = -7
x² - 7x + 6 = 0
Now we have:
a = 1
b = -7
c = 6
Plug in what we know into the formula:
x = [ -b ± √(b² - 4ac)] / (2a)
x = [ -(-7) ± √((-7)² - 4(1)(6))] / (2(1))
x = [ 7 ± √(49 - 24)] / (2)
x = [ 7 ± √(25)] / (2)
x = [ 7 ± 5 ] / (2)
x = 12 / 2 and x = 2/2
x = 6 and 1