Find 4ab when (a+b)=15 and (a-b)=12
2 answers:
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Answer:
Choices 1 and 4 are correct.
Step-by-step explanation:
We first need to find what the slope of the line is. That way, we can find out which possible answers are perpendicular to it:
Since we now have the slope, we need the negative reciprocal of it. Remember: if x is the slope, it's negative reciprocal will be . Therefore, if the line's slope is 3, then we need to find answers with a slope of
.
The first answer is correct, as you have marked. The second answer, while written a little weirdly, does show the slope as 3, which we know as wrong. The third choice is not correct, however. This equation is written in point-slope form, where. The only variable we have to worry about is m, which, in the third choice, is 3. The fourth answer is correct, which sounds weird at first. Let's put that equation into slope-intercept form:
Equations like these can be real sneaky, so it's important not to jump to conclusions with them.