Answer:
A. True
Step-by-step explanation:
One of the ways to check this is solving each side of the equation.
(5+4)+10=5+(4+10)
Remember PEMDAS.
Parenthesis first.
(9)+10=5+(14)
Now, you can drop the parenthesis and add the numbers together.
9+10=19
5+14=19
19=19
This is a true statement.
Hope this helps!
If not, I am sorry.
Answer:
5 cm
Step-by-step explanation:
We khow that the altitude of this triangle is 1cm shorter than the base
- Let H be our altitude and B our base and A the area of the triangle
- A= (B*H)/2 ⇒ 15=(B*H)/2
- H is 1cm shorter than B ⇒ B=H+1
- H*(H+1)/2=15 ⇒ H*(H+1)=30⇒ H²+H=30⇒H²+H-30+0
that's a quadratic equation . Let's calculate the dicriminant .
Let Δ be the dicriminant
- a=1
- b=1
- c= -30
- Δ=b²-4*a*c = 1²-4*1*(-30)=1+4*30=121≥0
- Δ≥0⇔ that we have two solutions x and y
- x= (-1-
)/2= (-1-11)/2= -6 - y= (-1+
)/2= 10/2 = 5
We have a negative value and a positive one
The altitude is a distance so it can't be negative
H= 5cm
X = -2
3 x -2 = -6
-6 -2= -8
|-8| = 8
-2 + 1= -1
|-1|=1