Question

If f(x) = x2 + 5x + 7, then the value of x for
which f(x) = f(x + 1) is
(A) 3
.(B) -6
(C) -3
(D) 6​

Answer 1

Answer:

given f(x) = f( x +1) that means put x +1 in x place

f(x) = x2 + 5x +1 -------------1

f(x+1) = (x+1)2 + 5(x+1) +7

f(x+1) = x2 +2x+1 +5x+5+7

f(x+1) = x2 +7x +13 ------- 2

from 1 and 2

put x = -3 in f(x) , f( x+1)

then f(x) = f( x+1) = 1

then final answer x = -3