We need to find the range of values for the expression: lala - 2blbl + 3lcic - 4didi + 5labcdlabcd
First, let's simplify each term by recognizing that for any non-zero number x:
IxIx = x*sign(x)
So our expression becomes:
a? sign(a) - 2b*sign(b) + 3c?sign(c) - 4d/sign(d) + 5(abcd)? sign(abcd)
Since we're looking for the range and a, b,c, and d are non-zero but can be any values, we can simplify by setting lal = IbI = Icl = Idl =1. This doesn't affect the range because we can
always scale these values to achieve any specific result within the range.
With this simplification, our expression becomes:
sign(a) - 2 sign(b) + 3-sign(c) - 4-sign(d) + 5 sign(abcd)
Let's denote:
sign(a) = A (either 1 or -1)
sign(b) = B (either 1 or -1)
sign(c) = C (either 1 or -1)
sign(d) = D (either 1 or -1)
Then sign(abcd) = A-B-C-D
Our expression is now:
A - +3C- 4D+ 5(A-B.C-D)
A - 2B + 3C - 4D + 5(A-B-C-D)
To find the maximum value, we need to maximize each term:
For A: choose A = 1 to get +1
For -2B: choose B = -1 to get +2
For 3C: choose C = 1 to get +3
For -4D: choose D = -1 to get+4
For 5(A-B.C-D): with A=1, B--1, C=1, D=1, we get 5(1-11-1) = 5(1) = +5
Maximum value = 1 + 2+3+4+5 = 15
To find the minimum value, we need to minimize each term:
For A: choose A = -1 to get -1
For -2B: choose B= 1 to get get-2
For 3C: choose C=-1 to get -3
For -4D: choose D= 1 to get 4
For 5(A-B-C-D): with A=-1, B=1, C--1, D=1, we get 5(-1-1-1-1) = 5(-1) = -5
Minimum value = -1 - 2-3-4 - 5=-15
Therefore, the range of the expression is [-15, 15], which means the range is 15 - (-15) = 30.
The answer is E) 30.