maths questions ?

Question

1) the square of a number is 12 more the original number. find two possible original numbers ?
2) if 15% of an amount is 24, what is the amount ?
3) zoe travelled 85km/h for 3 hours. how far did she travel ?

Answer 1

1)4 or -3
2)160
3)85*3 =255 km

Answer 2

1 ) Let the number be x.

Then, x^2 = 12 + x
So, x^2 - x - 12 = 0
So, (x - 4 ) ( x + 3 ) = 0
So, x = 4 or x = -3

2 ) Let the amount be x.

Then 15x/100 = 24 which gives x = 160.

3 ) Distance travelled = speed x time

= 85 x 3 = 255 km

Answer 3

2) If 15% is equal to 24... 5% is equal to 1/3 of 24, which is 8. Therefore 8*20 = 160
3) If Zoe travels 85km in 1 hr than she travels 255km in 3 hrs.
3*85

Answer 4

Answer 1:
Let the number be x

x^2 = x + 12
x^2 - x - 12 = 0
x^2 - 4x + 3x - 12 = 0
x(x - 4) - 3(x - 4) = 0
(x - 3)(x - 4) = 0

x = 3, 4

The numbers are 3 and 4


Answer 2:
Let the amount be x
15x/100 = 24
15x = 2400
x = 2400/15
x = 160

The amount is 160

Answer 3:
Distance = Time * Speed
= 3 * 85
= 255 km

Zoe travelled 255 km

Answer 5

1) x^2 = x+12
x^2 -x -12 =0
(x-4)(x+3)=0
x-4=0; x=4
x+3=0; x=-3

2) 0.15*x = 24 15% / 100% = 0.15
x= (24 / 0.15)
x=160

3) 85km per hour, then 3 hours would be
3*85= 255km
or write it on paper,
85km over 1hr * 3hr over 1 = 255km

you want the hours to cancel out to get
the distance (km)
(top and bottom "hr" cancel)

learn how we got the answers, then you can do it yourself on the test.

Answer 6

1) x^2 = x + 12 -> x*(x-1)= 12 -> x= 4 or x = -3
2) 15% of 160 = 24 Amount: 160
3) 85(Kms\h )*3(h) = 255 Kms

Answer 7

1)
Let n = original number

n^2 = n + 12
n^2 - n - 12 = 0
( n - 4 ) ( n + 3) = 0

n = 4 and
n = - 3
=====================
2)
Let x = the amount

15% of x = 24

.15x = 24
x = 24/.15
x = 160
====================
3)
distance = speed x time

d = 85 x 3
d = 255 km

Answer 8

1) 4 squared = 16
16-4=12
-3 squared = 9
9-(-3)=12

2) 24 is 15%.

1% = 24/15 = 1.6
100% = 1.6*100 = 160

3) Distance = Speed * time

= 85*3

=255km

Answer 9

1)4 or -3
2)=24*100/15=160
3)85*3 =255 km

Answer 10

1)
x^2 = x + 12
x^2 - x - 12 = 0
(x - 4)(x + 3) = 0
x = - 3, 4

2)
(15/100)24 = 360/100 = 3.6

3)
(85 km/hr)(3 hr) = 255 km