Answer: 7 × ( 3^n - 1 )
Step-by-step explanation:
This is a geometric progression which has its nth term to be
Tn = ar^n- 1. Now from the question given, the sequence are 7, 21, 63, 189. This is an example of a finite sequence, To find the common ratio, you divide the second term by the first term. So
r = 21/7
= 3. , a = 7
Now to find the nth term put the values in the formula above.
Tn =ar^n-1
= 7(3)^n - 1)
= 7 × ( 3^n - 1 ).
Note, it is not 21^n - 1.
Answer:
ok
Step-by-step explanation:
Answer:
y = -2
Step-by-step explanation:
Put x as -19 and solve for y.
2(-19) - 5y = -28
Multiply.
-38 - 5y = -28
Add 38 on both sides of the equation.
-5y = -28 + 38
-5y = 10
Divide both sides by -5.
y = 10/-5
y = -2
Follow PEMDAS.
You would first do your distributive property which is, -5(z+2). You would multiply -5 to z and -5 to 2 which will give you -5z + -10.
so now you have 2z-5z+ -10= -8 - 2z. Now you must isolate the variable. So subtract -8 to -10 which will give you -18.
Now you have the equation 2z-5z-18=-2z
Now combine like terms. 2z-5z= -3z
Now you have the equation -3z-18=-2z
Now you must move the -3z to the other side of the equal sign by adding the opposite which is +3z to -2z which will give you +1z
Now you have -18= 1z
Now you divide. -18 divided by 1 is -18.
So your final answer will be -18=z