log 2 (x+5) + log 2 (x+2) = log 2
(x+6)
We know that log x + log y = log
x*y
==> log 2 (x+5)(x+2) = log 2
(x+6)
We know that if log x = log y ==>
x=y
==> (x+5)(x+2) =
(x+6)
Open
brackets:
==> x^2 + 7x + 10 =
x+6
==> X^2 + 6X + 4
=0
==> x =[ -6 +
sqrt(36-16)]/2
= [-6 + sqrt(20)] /
2
= [-6 +
2sqrt(5)]/2
= -3 +
sqrt(5)
==> the answer is x = -3 +
sqrt(5)
No comments:
Post a Comment