Hello people ~factorise↷ x^2 + 4x –21
1 answer:
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Answer:
A
Step-by-step explanation:
We have the expression:
And we want to find its sign given that a>0 and b<0.
Notice that the expression is already negative since we have -4.
a>0 means that a is positive. Therefore, we can ignore it since it won’t do anything.
b<0 means that b is negative. Therefore, we will have two negatives being multiplied together. Hence, this will make a positive.
Therefore, the sign of our expression will be positive.
We can see this with an example. Let a=1 (1>0) and let b=-1 (-1<0). Then:
So, the sign is positive.
Hence, the answer is A.