sana.noor wrote:1) What is the value of xy?
a) y= x+1 b) y= x^2 +1
Each statement on its own is clearly insufficient.
Statements 1 and 2 combined:
Substituting
y=x²+1 into
y=x+1, we get:
x²+1 = x+1
x²-x = 0
x(x-1) = 0.
x=0 or x=1.
To determine the values of y, plug
x=0 and
x=1 into y=
x+1.
If x=0, then y=0+1 = 1, with the result that xy = 0*1 = 0.
If x=1, then y=1+1 = 2, with the result that xy = 1*2 = 2.
Since xy can take on different values, the two statements combined are INSUFFICIENT.
The correct answer is
E.
2) What is the value of xy?
a) y= x-1 b) y= x^2 -1
Each statement on its own is clearly insufficient.
Statements 1 and 2 combined:
Substituting
y=x²-1 into
y=x-1, we get:
x²-1 = x-1
x²-x = 0
x(x-1) = 0.
x=0 or x=1.
To determine the values of y, plug
x=0 and
x=1 into y=
x-1.
If x=0, then y=0-1 = -1, with the result that xy = 0(-1) = 0.
If x=1, then y=1-1 = 0, with the result that xy = 1*0 = 0.
Since in each case xy=0, the two statements combined are SUFFICIENT.
The correct answer is
C.
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