Answer:
f(4) =2
Step-by-step explanation:
f(x) = 2х^2 - 30,
Let x=4
f(4) = 2 (4)^2 -30
= 2*16 -30
=32-30
= 2
Answer:
n = 60.22
Step-by-step explanation:
Hello
To find Sn, we need to draw out equations for each a₇ and a₁₉
In an arithmetic progression,
Sn = a + (n-1)d
Where Sn = sum of the A.P
a = first term
d = common difference
a₇ = 32
32 = a + (7-1)d
32 = a + 6d ........equation (i)
a₁₉ = 140
140 = a + (19-1)d
140 = a + 18d .........equation (ii)
Solve equation (i) and (ii) simultaneously
From equation (i)
32 = a + 6d
Make a the subject of formula
a = 32 - 6d .....equation (iii)
Put equation (iii) into equation (ii)
140 = (32 - 6d) + 18d
140 = 32 - 6d + 18d
Collect like terms
140 - 32 = 12d
12d = 108
d = 108 / 12
d = 9
Put d = 9 in equation (i)
32 = a + 6(9)
32 = a + 54
a = 32 - 54
a = -22
When Sn = 511
Sn = a + (n - 1)d
Substitute and solve for n
511 = -22 + (n-1) × 9
511 = -22 + 9n - 9
511 = -31 + 9n
511 + 31 = 9n
542 = 9n
n = 542 / 9
n = 60.22
Answer:
x = 2
Step-by-step explanation:
Simplify both sides of the equation.
−20 = − 4x − 6x
−20 = −4x − 6x
−20 = (−4x − 6x)(Combine Like Terms)
−20 = −10x
Flip the equation.
−10x = −20
Divide both sides by -10.
-10x/-10 = -20/-10
x = 2
Answer:
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