= -(x^2-4x+4)
= -(x-2)^2
Prove 3(x+1)(x+7)-(2x+5)² is never positive
So,
3(x+1)(x+7)-(2x+5)(2x+5)
=3(x²+8x+7)-(4x²+20x+25)
=3x²+24x+21-4x²-20x-25
=-x²+4x-4
8 answers
The answer above didn't work
Sorry It actually did
I don't know what you mean by it "didn't work." It just shows that the expression is never positive.
(x-2)^2 is a square, so it is always positive
So, -(x-2)^2 is never positive.
Trying to plug a formula into a request for a proof will never work. The logic is what counts.
(x-2)^2 is a square, so it is always positive
So, -(x-2)^2 is never positive.
Trying to plug a formula into a request for a proof will never work. The logic is what counts.
this was extremely useful. thank you
Hi, you information was really useful but for some reason I only got 4 marks out of 5 on mathswatch, do you know why?
THANK YOU SM
3(x + 1)(x + 7) - (2x + 5)(2x + 5)
= 3(x² + 8x + 7)- (4x²+ 20x + 25)
= 3x² + 24x + 21- 4x²- 20x- 25
= -x² + 4x - 4
= -1(x - 2)²
A squared number is always positive, but when you multiply it with a negative number, it is always negative, never positive.
^This will give you all 5 marks on Mathswatch. Hope it helps :)
= 3(x² + 8x + 7)- (4x²+ 20x + 25)
= 3x² + 24x + 21- 4x²- 20x- 25
= -x² + 4x - 4
= -1(x - 2)²
A squared number is always positive, but when you multiply it with a negative number, it is always negative, never positive.
^This will give you all 5 marks on Mathswatch. Hope it helps :)
1 answer