Trikky Equations Review

Linear

100

-4(x-6)=-3

x=27/4

200

2x+5=8-6x  

x=3/8

300

3(x − 2) + 5(x + 1) = 15

x=2

400

Five times a certain number x is equal to 12 more than the number. Find the number.

x=3

500

The formula to convert degrees Celsius, C, to degrees Fahrenheit, F, is F = 9/5 C+32. Find C when F = 100.

x=37 7/9

Quadratics

100

x² = 225

x=-15,15

200

Solve (7x − 4)²=0

x= 4/7

300

Solve x² − 8x − 20=0

x= -2, 10

400

Use the quadratic formula to solve.

6x² + 7x − 5 = 0

x= -5/3  or x =1/2

500

Solve 8x² − 11x + 3=0

x= 3/8, 1

Simultaneous

100

Solve y = 2x − 3 and

y = 2 − 3x simultaneously.                 

x=1, y=-1

200

Solve x = 5 − y and 3x − 7y = −1 simultaneously using the substitution method.

x=17/5,  y= 8/5

300

Use the elimination method to solve 3x − 5y = 21 and 5x − 4y = 22 simultaneously.

x=2, y=-3

400

Solve simultaneously y = x² + 15x + 13 and 

y = 3x − 7.

x= -10, y =-37  or  x= -2, y =-13

500

John is two years older than Paula. Three times John’s age plus four times Paula’s age is 55 years. How old are John and Paula?

Paula is 7, John is 9

Fractional

100

x/7 + 9 = −3

x=-84

200

(2x − 1)/3 =4

x=6.5

300

x/3 - x/6 = 4

x=24

400

x - x/4 =2/3

x=8/9

500

3x/2 - (x+1)/3 =-1/5

x=4/35

Other

100

4x + 1 ⩾ 2

x ⩾1/4

200

3 − 2x < 14 + 5x

x>-11/7

400

x⁴ − 29x² + 100=0

x= -5, -2, 2, 5

500

In my purse I have 21 coins, all of which are either 5-cent or 20-cent coins. Their total value is $2.25. How many 20-cent coins do I have?

13 x 5c coins

8 x 20c coins