How do you solve this system of equations using the addition method:
4
x
−
y
=
−
4
;
5
x
+
2
y
=
−
18
?
Algebra
1 Answer
IDKwhatName
Jun 30, 2017
x
=
−
2
,
y
=
−
4
Explanation:
Right now, you have:
4
x
−
y
=
−
4
5
x
+
2
y
=
−
18
To make this easier, you must get rid of one variable, in this case I will remove
y
, to do this you must make the y-values in both equations the same.
To do this, I will multiply the whole of
4
x
−
y
=
−
4
by 2 to give
8
x
−
2
y
=
−
8
We now have:
8
x
−
2
y
=
−
8
5
z
+
2
y
=
−
18
All we need to do now is
(
8
x
−
2
y
+
5
x
+
2
y
)
=
(
−
18
−
8
)
≡
13
x
=
−
26
.
Divide both sides by 13 to find
x
:
13
x
=
−
26
13
x
13
=
−
26
13
x
=
−
2
Now put your value for
x
into either equation:
4
(
−
2
)
−
y
=
−
4
−
8
−
y
=
−
4
y
=
−
8
+
4
y
=
−
4
x
=
−
2
;
y
=
−
4
Answer link
The greatest common factor of 35 and 42 is 7
35/7 is 5 and 42/7 is 6
Hope this helps!
Answer: About 513 feet
A more accurate value is roughly 512.575960394824
==============================================================
Explanation:
With many trig problems, a diagram should help steer you in the right direction. See below.
The red angle is the angle of depression. It's formed by starting off looking straight horizontal, then we look down 26 degrees. The blue angle adds to the red angle to get 90, so we can see that 26+64 = 90. Or you could say 90-26 = 64.
The goal is to find the value of x, which is the length from B (the lighthouse base) to point C (the ship's location).
The lighthouse is 250 ft tall, meaning AB = 250
We'll use angle BAC, or angle A for short, as the reference angle. This is the blue angle in the diagram.
We have a known adjacent side (AB = 250) and an unknown opposite side (BC = x). We use a tangent ratio to tie these sides together with the reference angle in question. This way we can solve for x.
-------------------
tan(angle) = opposite/adjacent
tan(A) = BC/AB
tan(64) = x/250
250*tan(64) = x
x = 250*tan(64)
x = 512.575960394824
x = 513
The distance from B to C is roughly 513 feet.
I'm rounding to the nearest whole number because the other values given to you are whole numbers.
It is 1,000 bigger than the one in the tens place. 5,000 compared to 50