Answer:
2. x = 47
3. x = 2
Step-by-step explanation:
These problems involve proportions, or equivalent ratios. You can solve for 'x' in each by using cross-multiplication and division.
2. 28(7) = 4(x + 2)
Distribute = 196 = 4x + 8
Subtract 8 from both sides: 196 - 8 = 4x + 8 - 8 or 188 = 4x
Solve for x: x = 47
3. 2(2x + 7) = 11(3x - 4)
Distribute: 4x + 14 = 33x - 44
Add 44 to both sides: 4x + 14 + 44 = 33x - 44 + 44 or 4x + 58 = 33x
Subtract 4x from both sides: 4x + 58 - 4x = 33x - 4x or 58 = 29x
Solve for x: x = 2
Answer:
the common ratio is either 2 or -2.
the sum of the first 7 terms is then either 765 or 255
Step-by-step explanation:
a geometric sequence or series of progression (these are the most common names for the same thing) means that every new term of the sequence is created by multiplying the previous term by a constant factor which is called the common ratio.
so,
a1
a2 = a1×f
a3 = a2×f = a1×f²
a4 = a3×f = a1×f³
the problem description here tells us
a3 = 4×a1
and from above we know a3 = a1×f².
so, f² = 4
and therefore the common ratio = f = 2 or -2 (we need to keep that in mind).
again, the problem description tells us
a2 + a4 = 30
a1×f + a1×f³ = 30
for f = 2
a1×2 + a1×2³ = 30
2a1 + 8a1 = 30
10a1 = 30
a1 = 3
for f = -2
a1×-2 + a1×(-2)³ = 30
-10a1 = 30
a1 = -3
the sum of the first n terms of a geometric sequence is
sn = a1×(1 - f^(n+1))/(1-f) for f <>1
so, for f = 2
s7 = 3×(1 - 2⁸)/(1-2) = 3×-255/-1 = 3×255 = 765
for f = -2
s7 = -3×(1 - (-2)⁸)/(1 - -2) = -3×(1-256)/3 = -3×-255/3 =
= -1×-255 = 255
Answer:
<em>10x + 50 =1 +5</em>
<em>10x=6-50</em>
<em>10x=-44</em>
<em>x=-4.4</em>
Step-by-step explanation:
14 + 5(x+3)-7
14 + 5x +15 -7
5x + 22
