![]() ![]() To be a positive- or they're both going to be Positive- a positive times a positive is going That product is greater than 0, what do we know about a and b? Well, we know that they The product a times b, and if someone were to tell you And I'll do a littleīit of an aside here. So let's think about how weĬould reason through this. Would be equal to 0, because 0 times anything is 0. Things were equal to 0, then this entire expression Now, if this wasĭo we get this equals 0? If either of these Their product is negativeġ0, their sum is positive 3. So if you have positiveĥ and negative 2, that seems to work out. 2 and 5 seem tempting,īecause their difference is 3. Think of two numbers whose product is negative 10Īnd whose sum is positive 3. Sign right over here, we'd want to factor this thing. Now, this gets us into aįorm that we're more used to seeing quadratic ![]() Same thing to both sides, it won't change the inequality. Plus 3x minus 10 is still going to be greater than. ![]() Into a form that we're more comfortable with, is The reasoning might departure a little bit from Get to the end, try to reason through it, because We want to figure outĪll of the x's that would satisfy this inequality. Solve the inequality x squared plus 3x is greater than 10. Since the answer is in between -3 and -5, the solutions should be X>-5 or X-5 or x<-3 When you write this in interval notation, you'll have (-∞,-5)U(3,+∞) Since our values are -5 and 3, the solution will be -∞. According to the wavy curve method, when you have "x" is greater than ( >) something, then you leave the values between the two numbers and take all the other values. When you have two values, the method I use to find the interval is using the wavy curve method ( It would be tough for me to explain it, better to understand it visually than by writing). Now the final part is figuring out the interval. So, you'll have two values, x > 3 or x > -5. Now you can multiply the denominator with zero since even if your "x" is negative is will become positive since it's been squared. And due to this, if x was negative you'd have to flip the inequality but like I said you do not know for sure. This is because you are unsure of whether the value of "x" is positive or negative. When you have an inequality like this, you can't multiply the denominator with 0 and make the simplification easier. ![]()
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