Step-by-step explanation:
Sn=n/2(2a+(n-1)d)
910=n/2{2a+(n-1)d}
1820=n{2a+(n-1)d}
1820=20{2a+(20-1)d}
1820=20{2a+19d}
91=2a+19d
An=a+(n-1)d
95=a+(20-1)d
95=a+19d
91=2a+19d
---------------
4=-a
a=-4
91=2a+19d
91=2(-4)+19d
91=-8+19d
91+8=19d
99=19d
d=99/19
A=-4
Answer:
0.375
Step-by-step explanation:
Answer:
-3
Step-by-step explanation:
2a - 6 = 4a
subtract 2a giving you -6 = 2a
divide by 2 from both sides so that a will be by itself
giving you -6 ÷ 2 = a
-6 ÷ 2 = -3
so a = -3
Answer:
x+y/4 = 1/2
x-3y/3 = 2
move variables to one side:
multiply the first equation by 4 to get: x+y =2
and the second equation by 3 to get: x-3y =6
then subtract the equations to cancel out x:
x+y = 2
- x-3y = 6
then u get
y--3y = 2-6
4y = -4
y=-1
substitute to solve for x:
x-1 / 4 =1/2
x-1 = 2
x=3
check:
3+-1
2/4= 1/2
correct!!!
