Infinitely many because if you subtract 7x from both sides, you get 4 = 4, which is true at all times no matter what x is.
This question is easier than it seems. If there are 9 consecutive integers with the mean being 16, then 16 must be the median. So just add four on top and four below 16 to give you your range of 9 values, 12-20. 12+13+14+15+16+17+18+19+20=144, 144/9=16. So the mean of the first four numbers is (12+13+14+15)/4= 13.5. If you check, 13.5 is also the median of these four numbers.
That is correct I think it is
Answer:
18) 6x^2-7x-5
19) 20x^2+17x-63
20) 18x^2-20x+2
21) 5x^2+42x+16
Step-by-step explanation:
Perimeter=length×breadth
18) (3x-5)(2x+1)
=6x^2+3x-10x-5
=6x^2-7x-5
19) (4x+9)(5x-7)
=20x^2-28x+45x-63
=20x^2+17x-63
20) (18x-2)(x-1)
=18x^2-18x-2x+2
=18x^2-20x+2
21) (5x+2)(x+8)
=5x^2+40x+2x+16
=5x^2+42x+16
