First verify it holds for n=1
then you are allowed to assume it holds for n and you can start with the induction step
for n+1 instead of inserting it into the equation, add it to both sides and transform it to the original formula to proof its equality

this equals the original formula if you had inserted n+1, proving the correctness
Answer:
288 cubic feet
Step-by-step explanation:
add the 3 blocks.
block 1: 12*6*2=12*12=144
block 2: (12-4)*2*6=8*2*6=8*12=96
block 3: (12-4-4)*6*2=4*12=48
add them up:
144+96+48
288 cubic feet
with help of calculator
The answer is 3x squared -11x-10
Sorry, it's late, and I'm a bad explainer.
The error is adding (2x-12) with x and 30. This is wrong because you are adding the angles inside the triangle and you are assuming that (2x - 12) is the unlabeled angle INSIDE the triangle, when it is the exterior angle/outside of the triangle.
A straight line is also 180°.
(2x - 12) + ? = 180
30 + x + ? = 180
If you look at the equations, and put parentheses around 30 + x, (30 + x) and (2x - 12) should be the SAME NUMBER. So you could set them equal to each other to find x. (or you could also look at the picture and see that they both need/are missing the same angle)
2x - 12 = 30 + x
x = 42
Now you plug 42 into the exterior angle equation
2(42) - 12 = 84 - 12 = 72°
Lets find that number:
3 < x < 4
that can easily be thought as 3.5
<span>3 < 3.5 < 4
</span>now lets change the decimal to a mix number:
3.5 = 3 + 0.5
= 3 + 5/10
= 3 + 1/2
= 3 1/2