IF x(X-5)(X+2)=0 is x negative?
1.x sq.2-7x is not equal to 0
2. x2-2x-15 is not equal to O.
Please help. OA is [img]c[img]
Question:( x<0 )?
Interpret fact to get that x=0,5 or -2, in the first 2 cases we have NO, in the last one we have a YES.
So we need more data.
(1) x*sqrt(7x) != 0
(correct me if I read this wrong)
This means that x != 0 & that sqrt(7x) != 0. I don't think this is an Official question (GRRRR) or a very
poorly formulate one, but we can't test x=-2 as the square root of a negative number is a complex number... So if we can use complex numbers, insufficient, and if we aren't allowed to take the square root of a negative number, sufficient, as X can only be 5. But I'm going to go with Insufficient.
(2) x^2 - 2x - 15 != 0
Factorize the quadratic,x^2 - 5x + 3x - 15 != 0x(x - 5) + 3(x - 5) != 0(x-5)(x+3) !=0
So X can't be 5 or -3, but it can still be 0 or -2. Insufficient.
From original equation: x=0,5,-2
1 eliminates 0
2 eliminates 5
Only x=-2 remains
Final Answer, C