-4 + -7= -11
When adding negative numbers if the are both negative then you add them. When you have a negative and a positive you subtract. In this problem they just took out the plus sign.
The prime numbers on the dice are 1,2,3,5 and 7 , the theoretical probability is

, which is 62.5%, the number of prime numbers in the outcome is 15, so the experimental probability is

, which is 75%, the difference between the experimental probability and the <span>theoretical probability is 12.5%.</span>
You don't have a question in there but I can tell you that the quadratic formula that is shown is not quite correct.
<span>x = -b ± √b2 - 4ac 2a
For one thing, the first 3 terms should ALL be divided by 2a
The square root symbol should be extended from b^2 through 4ac
The division symbol is missing.
So the quadratic formula SHOULD read:
x = [-b +- sq root (b^2 - 4ac) ] / 2a
Also I have attached a graphic of the quadratic formula.
</span>
Step-by-step explanation:
try to factor them anx than set each bracket to 0 the negative one would not work
This is true. All numbers that end in zero or five are divisible by 5, and a number that ends in zero is even, and all even numbers are divisible by two.