Question

if x is less than 5 then √(x^2-10x+25) +x+7 is equal to

Answer 1

Answer:

All answers are ok, I just wanted to add a simpler way to think about it, instead of “going by the book”.

So, I can see that if x^2 + 10x could make -25, then adding the +25 would lead to zero.

Since the sign of x does not matter when talking x^2 (either a minus or a plus x would result to a positive number if squared) this means that x^2 is positive and I have to reach my -25 target by subtracting a big number. So I thought if x^2 is 25 and 10x is -50 then I got my -25:

-5^2 +10(-5) = 25 - 50 = -25 my desired target which, when added to the rest +25 would give 0.

There you go, -5.