Engineer1
Chetan2u
Hi
The solution is correct as given. The solution mentions that x>7/3 is not a possible range.
Substitute x=1 in the equation and you will realise x<7/3 is incorrect
Actually whatever you get x<7/3 or x>7/3 is a flawed solution and therefore is discarded in the end to get range of x as only x<-1.
chetan2u I do not understand this statement. "Actually whatever you get x<7/3 or x>7/3 is a flawed solution and therefore is discarded in the end to get range of x as only x<-1"
Hello
Engineer1 I am not sure how
chetan2u got x>7/3 but I guess he means that it doesn't matter if x>7/3 or x< 7/3 because in either case those ranges don't make the inequality true and only x<-1 holds true.
I have solved this question as following:
Statement 1 tells us that
|x − 4| < −2x + 3We get two cases: either x-4<-2x+3 or x-4>2x-3
After further simplification, we get
either x<7/3 or x<-1And at this point, what was alarming to me is to see that the two ranges point in the same direction, because usually when you have |something| <or> something, we either get a conjonction of values, which means a situation where the eventual values of x will be inside a specific interval or a disconjonction, with values of x being in two opposite parts of the number line, in a symmetrical manner and heading towards infinity.
Therefore, I leaned towards verifying the correctness of the obtained ranges.
When you pick for example x=1 which is within the range x<7/3, you find that it doesn't make the inequality true because 3 can never be less than 1. Therefore x<7/3 is not a valid range for this inequality.
On the other hand if you pick any value of x less than -1, the inequality will hold true.
Hence the range of solutions of the inequality in statement 1 is x<-1.
And since the question asks is x>1 you can answer with a definite No.
Statement 1 is sufficient. Statement 2 tells us that
|x − 4| > |x + 4|Which translates to sqrt(x-4)^2 > sqrt(x+4)^2
(Always keep in mind the following rule: sqrt x^2 = |x|)Squaring both sides we get, (x-4)^2 > (x+4)^2
Simplifying further, (x-4)^2 - (x+4)^2 > 0
(A quadratic in the form (a^2 - b^2)= (a-b) (a+b) )(x-4+x+4) (x-4-x-4)>0
-16x>0
Therefore x<0
Again this tells us that the answer to our question is NO, no x is not greater than 1 because it is less than 0 as find out above.
Hence statement 2 is also sufficient.Correct answer is DHope this helps!