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Question # Let a, b and c be a real numbers such that a>0, b<0 and c<0. Find the sign of each expression.a) -ab) bcc) a-bd) ab+ac

Negative numbers and coordinate plane
ANSWERED Let a, b and c be a real numbers such that $$a>0, b<0$$ and $$c<0$$. Find the sign of each expression.
a) -a
b) bc
c) a-b
d) $$ab+ac$$ 2021-03-10

(a) Here $$a>0$$ $$\displaystyle\Rightarrow$$ −a will be a negative number.
Thus, sign of -a is negative .
(b) It is known that product of two negative number will be positive.
As $$b<0$$ and $$c<0$$ $$\displaystyle\Rightarrow$$ $$bc>0$$.
Thus, sign of bc is positive.
(c) It is known that when a negative number is subtracted from a positive number, the resultant number will be positive.
Here $$a>0,b<0$$ $$\displaystyle\Rightarrow$$ $$a−b>0.$$
Thus, sign of a-b is positive.
(d) Here
$$a>0,b<0$$ $$\displaystyle\Rightarrow$$ $$ab<0$$
$$a>0,c<0$$ $$\displaystyle\Rightarrow$$ $$ac<0$$
So ac and bc negative.
It is known that sum of two negative number will be negative.
Thus, $$ab+ac<0.$$
Thus, sign of $$ab + ac$$ is .