Question

The roots of 7x^2 + x - 5 = 0 are a and b. Compute (a - 4)(b - 4). Thank you!

Answer 1

Answer:

Step-by-step explanation:

a = 7 ;  b = 1 ;  c = -5

D = b² - 4ac

  = 1 - 4*7*(-5)

  = 1 + 140

  = 141

x =( - b ± √D ) / 2a

 = (-1 ± √141)/2*7

 = (-1±√141) / 14

$a = \frac{-1+\sqrt{141} }{14}= \frac{-1+11.87}{14}= \frac{10.87}{14}=0.78\\\\b = \frac{-1-\sqrt{141}}{14}= \frac{-1-11.87}{14}= \frac{-12.87}{14}=3.59$

(a -4 )(b -4) = (0.78 - 4)(-3.59-4) = (-3.22)(-7.59)

= 24.4398