Factor each one to see what they have in common:
15x² = 3 * 5 * x * x
42x³ = 2 * 3 * 7 * x * x * x
They both have: 3, x, x
When multiplied together, 3 * x * x = 3x²
Answer: 3x²
23×$1.25=28.75
15×$1.75=26.25
Then add both totals to get $55
Answer:
cot 840° = 
Step-by-step explanation:
First, we must bring the value of 840° down to a value less than 90°.
To do that, we have to consider how many full rotations 840° is on the coordinate plane.
Start by dividing by 360°, since that is one full rotation.
840°/360°=2 R.120
So now we know that 840° is 120° extra, and therefore, the two calues will be equal.
So, cot840°, will be the same as cot120°
But now we need to make 120° a value less than 90°. So we can divide by 90°
120°/90°, and you get 1 R.30°
So now we also know that cot120° = cot 30°
Using your trigonometric table, we see that cot 30° = 
Hope this helped
Answer:
-2.33333333333333333333333
Step-by-step explanation:0