Quiz · Medium
Solve for x, work with slope and lines, solve systems of equations, inequalities and absolute value equations, plus a few word problems. Every answer shows the steps.
Solve for x:
Subtract 7 from both sides: . Divide by 3: . Check: . comes from adding 7 instead of subtracting.
Solve for x:
Distribute: . Subtract 3x: . Add 10: , so . Getting means the 5 was not distributed to the 2 ().
Solve for x:
Add 3: . Multiply both sides by 4: . Dividing 5 by 4 (giving 1.25) undoes the operation the wrong way.
Solve for x:
Distribute: . Combine like terms: , so and . 4.5 comes from writing instead of .
Solve for x:
Multiply every term by the LCD, 6: . Subtract 3x and 6: . Clearing fractions first avoids most mistakes; just remember to multiply the constants too.
What is the slope of the line through (2, 3) and (6, 11)?
. puts run over rise. 8 is only the change in y.
Which equation describes the line with slope −3 that passes through (1, 4)?
Point-slope form: , so . Check: at x = 1, y = 4. Using 4 as the intercept forgets that (1, 4) is not on the y-axis.
What is the slope of a line perpendicular to ?
Perpendicular slopes are negative reciprocals, so their product is −1: . A parallel line would have the same slope, 2.
Where does cross the x-axis?
(4, 0)
(0, −3)
(−3, 0)
(0, 4)
On the x-axis, y = 0: , so x = 4, giving (4, 0). (0, −3) is the y-intercept, found by setting x = 0.
Solve the system: and
Add the equations (elimination): , so x = 7. Then , so y = 3. Check the second equation: 7 − 3 = 4. Swapping x and y fails that check.
Solve the system: and
Substitute: , so , and y = 2. Then . Check: .
How many solutions does this system have: and ?
No solution
Exactly one
Exactly two
Infinitely many
Doubling the first equation gives , which contradicts . The lines have the same slope (−2) but different intercepts, so they are parallel and never meet. Infinitely many would need identical lines.
Solve the inequality:
Subtract 5: . Divide by −2 and flip the inequality sign: . Forgetting the flip when dividing by a negative gives . Check with x = −4: .
Solve:
or
only
or
only
The expression inside can be 7 or −7: gives x = 10, and gives x = −4. Both are 7 units from 3 on the number line.
Solve for h.
Multiply both sides by 2: . Divide by b: . Check with b = 4, h = 3: A = 6, and .
A phone plan costs $20 per month plus $0.10 per text. One month's bill is $35. How many texts were sent?
350
15
550
150
Write . Subtract 20: , so . 350 comes from adding the $20 instead of subtracting it.
The sum of three consecutive integers is 51. What is the smallest of them?
17
15
16
18
Let them be n, n + 1, n + 2. Then , so and n = 16. The integers are 16, 17, 18. 17 is the middle one (51 ÷ 3).
Solve for x:
Subtract 0.3x: . Add 1.2: , so x = 10. Tip: multiply everything by 10 first to get . 2.5 comes from adding the x terms (0.8x = 2).