Cho tam giác ABC vuông tại A, có BD là phân giác của . Trên cạnh BC lấy điểm M sao cho BA = BM. a. Tính độ dài đoạn BC. Biết AB = 6cm, AC = 8cm. b. Chứng minh \Delta ABD = \Delta DMB. Từ đó suy ra MD \bot BC c. Đường thẳng MD cắt AB tại F. Gọi H là trung điểm của FC. Chúng minh rằng ba điểm D, B, H thẳng hàng. d. Giả sử \widehat {ACB} = {30^0}. Chứng minh rằng D là trọng tâm tam giác BFC

8

step-by-step explanation:

this is a subtraction problem.

10 - 2 = 8

let's cover over the formula of the vertex:

y = a(x – h)^2 + k

in this formula, (h,k) are the vertex, always remember that the positive or negative value of the vertex is based on the sign it has.

for example, if the vertex is -3,-6 then both the x and y value would have the positive sign attached to it and if it were a positive x and y value, then a negative sign would be attached to it.

with that being said, for our problem the x value is a positive one so we are looking for a number with a negative sign next to it, in this case the first and second choice.

however, for the first answer choice it isn't quite part of the formula so we know that the answer choice correctly displays the x value.

to confirm, we can see if the -1 fits correctly with the second answer choice, and as mentioned above a negative number will have a positive sign attached to it. so, for our problem we can see that -1 has been changed to +1, so we can confirm that the second answer choice is correct.

hence, our final answer is y=(x - 1)^2 + 1

27 + 13x + 15 = (x + 5)( =

step-by-step explanation:

27 + 13x + 15 = (x + 5)( = 27 + 13x + 15 = (x + 5)( = 27 + 13x + 15 = (x + 5)( =