Answer:
D
Step-by-step explanation:
a perfect square trinomial is

factorized is

so as you can see option A and B can't be, because they have -49y^2 and it has to be plus
so the other options are C and D
in the trinomial a=4 and b=\pm 7
the roots of a^2 and b^2

so it's option d with b=-7

Answer:
Bag of windflower bulbs costs $8.50
Package of crocus bulbs costs $17.60
Step-by-step explanation:
Let $x be the price of one bag of windflower bulbs and $y be the price of one package of crocus bulbs.
1. Mark sold 2 bags of windflower bulbs for $2x and 5 packages of crocus bulbs for $5y. In total he earned $(2x+5y) that is $105. So,
2x+5y=105
2. Julio sold 9 bags of windflower bulbs for $9x and 5 packages of crocus bulbs for $5y. In total he earned $(9x+5y) that is $164.50. So,
9x+5y=164.50
3. You get the system of two equations:

From the first equation

Substitute it into the second equation:
9x+105-2x=164.50
7x=164.50-105
7x=59.5
x=$8.50
So,
5y=105-2·8.5
5y=105-17
5y=88
y=$17.60
Answer:
15cm
Step-by-step explanation:
All you need to do for this is divide the perimeter (60) by the number of sides on a square (4). 60÷4=15
Huh? What do you mean I don't understand