|3x+7| \(\geq{2x+12}\)
The critical points of the above equation are -6 and \(\frac{-7}{3}\)
To find the critical Points equate the either side of the equations to 0
i.e. 3x + 7 = 0 ==> x =\(\frac{-7}{3}\)
and 2x + 12 = 0 ==> x = -6
So 3 ranges to consider :
Range 1 : x<-6Take any value in this area say for Ex : -7
Look for the Expr. inside mod 3x +7 will become 3(-7)+7
So this expression will evaluate to a -ve value
Therefore this equation can be written as :
(-1)(3x+7) \(\geq{2x+12}\)
-3x-7 \(\geq{2x+12}\)
-5x \(\geq{19}\)
x \(\leq{-19/5}\)
Now this range is x<-6 , so based on the solution all values of x in this range should satisfy the equation
Range 2 : -6<x<\(\frac{-7}{3}\)Take any value in this area say for Ex : -5
Look for the Expr. inside mod 3x +7 will become 3(-5)+7
So this expression will evaluate to a -ve value
Therefore this equation can be written as :
(-1)(3x+7) \(\geq{2x+12}\)
-3x-7 \(\geq{2x+12}\)
-5x \(\geq{19}\)
x \(\leq{-19/5}\)
Now this range is -6<x<\(\frac{-7}{3}\) , so only values of x \(\leq{-19/5}\) will satisfy
Range 3 : x>\(\frac{-7}{3}\)Take any value in this area say for Ex : -1
Look for the Expr. inside mod 3x +7 will become 3(-1)+7
So this expression will evaluate to a +ve value
Therefore this equation can be written as :
(3x+7) \(\geq{2x+12}\)
3x+7 \(\geq{2x+12}\)
3x-2x \(\geq{5}\)
x \(\geq{5}\)
Now this range is x>\(\frac{-7}{3}\), so only values of x\(\geq{5}\) will satisfy
So Combining ,x \(\leq{-19/5}\) OR x \(\geq{5}\) will hold true
Hence Answer : D