Question #1eddb

1 Answer
Jul 2, 2017

#(x + 68)/(x + 8) >= 5#

We first multiply both sides by #(x + 8)^2# as this is a positive quantity and won't change the inequality sign

i.e. #(x + 68)(x + 8) >= 5(x + 8)^2#

=> #(x + 68)(x + 8) - 5(x + 8)^2 >= 0#

=> #(x + 8)[(x + 68) - 5(x + 8)] >= 0#

so, #(x + 8)(28 - 4x) >= 0#

or, #4(x + 8)(7 - x) >= 0#

This function is an inverted parabola which intersects the x-axis at -8 and 7

Hence, it is above the axis, or on it for #-8 < x <=7#

Note, we cannot have x = -8 as this value is excluded from the domain.

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