The roots of \(7x^2 + x - 5 = 0\) are \(a\) and \(b\). Compute \((a-4)(b-4)\)
Thanks :D
(x-a)(x-b) ~~ 7 x^2 + x - 5
x^2 - ax - bx + ab = 7x^2 + x -5
7 x^2 - x* 7(a+b) + ab = 7x^2 + x -5
sooo: ab = -5 a + b = 1/7
(a-4)(b-4) = ab - 4a - 4b + 16
ab - 4 (a+b) + 16
-5 -4(1/7) + 16 = .................
+84 
