Answer:
15
Step-by-step explanation:
If A||B then the sum of given angles must be equal to 180°
2x + 5 + 5x - 80 = 180 add like terms
7x - 75 = 180 subtract 75 from both sides
7x = 105 divide both sides by 7
x = 15
Answer:
(x, y) = (- 2, 5)
Step-by-step explanation:
given the 2 equations
3y = 11 - 2x → (1)
3x = y - 11 → (2)
Rearrange (2) expressing y in terms of x
add 11 to both sides
y = 3x + 11 → (3)
Substitute y = 3x + 11 into (1)
3(3x + 11) = 11 - 2x
9x + 33 = 11 - 2x ( add 2x to both sides )
11x + 33 = 11 ( subtract 33 from both sides )
11x = - 22 ( divide both sides by 11 )
x = - 2
Substitute x = - 2 in (3) for corresponding value of y
y = (3 × - 2) + 11 = - 6 + 11 = 5
As a check
substitute x = - 2, y = 5 into (1) and (2) and if the left side equals the right side then these values are the solution.
(1) : left side = (3 × 5) = 15
right side = 11 - (2 × - 2) = 11 + 4 = 15 ⇒ left = right
(2) : left side = (3 × - 2 ) = - 6
right side = 5 - 11 = - 6 ⇒ left = right
solution = (- 2, 5 )
Answer:
-3.6
Step-by-step explanation:
Simplifying
7 + 3x + 4 = 0
Reorder the terms:
7 + 4 + 3x = 0
Combine like terms: 7 + 4 = 11
11 + 3x = 0
Solving
11 + 3x = 0
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '-11' to each side of the equation.
11 + -11 + 3x = 0 + -11
Combine like terms: 11 + -11 = 0
0 + 3x = 0 + -11
3x = 0 + -11
Combine like terms: 0 + -11 = -11
3x = -11
Divide each side by '3'.
x = -3.666666667
Simplifying
x = -3.666666667
Question 14, Part (i)
Focus on quadrilateral ABCD. The interior angles add to 360 (this is true for any quadrilateral), so,
A+B+C+D = 360
A+90+C+90 = 360
A+C+180 = 360
A+C = 360-180
A+C = 180
Since angles A and C add to 180, this shows they are supplementary. This is the same as saying angles 2 and 3 are supplementary.
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Question 14, Part (ii)
Let
x = measure of angle 1
y = measure of angle 2
z = measure of angle 3
Back in part (i) above, we showed that y + z = 180
Note that angles 1 and 2 are adjacent to form a straight line, so we can say
x+y = 180
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We have the two equations x+y = 180 and y+z = 180 to form this system of equations
Which is really the same as this system
The 0s help align the y terms up. Subtracting straight down leads to the equation x-z = 0 and we can solve to get x = z. Therefore showing that angle 1 and angle 3 are congruent. We could also use the substitution rule to end up with x = z as well.
