Question

1. A phone is reduced by 30% to a price of £120. Calculate the original cost of the system.

2. What is of £240?
3. Write 48 as a product of its prime factors in index form.
4. Factorise x² -2x-35.
5. Write 210,000,000 in standard form.
6. Solve: 2x + 7 ≤ -1.
7. Use prime factors to find the lowest common multiple of 270 and 84.
8. List the first 5 terms of the sequence 8n + 2.
9. Find the total perimeter of the sector shown, correct to one decimal place.
6cm
124°
10. Calculate (4.85x1025)+(1.7×10¹9), giving your answer in standard form correct to two
significant figures.

Answer 1

1. Step by step explanation:- Since 120$ is obtained by reducing the price by 30% that is subtracting ORIGINAL COST from its 30%.

In order to obtain the Cost Price we shall add back the 30% to 120$ to obtain the Cost Price -

120+30%*120 = 120+36= 156 $ . (Ignore the currency. Answer remains unaffected )

2. Question is incomplete.

3. 48=2*2*2*2*3

4. Factorization of x^2-2x-35 is

=x^2-7x+5x-35 (-7x+5x= -2x)

=x(x-7)-5(x-7) (Taking x common from the first () and 5 from the second bracket)

=(x-5)(x-7)

Factors are 7 and 5.

5. 2.1*10^8

6. For this question it is to be assumed that -

2x+7=-1

Now normally solving the equation we get

2x=-1-7

=> 2x= -8

=> x= -4

7. Multiples of 270 = 3*3*3*2*5

Multiples of 84 = 2*2*3*7

Common multiples = 2*3=6

8. First 5 terms can be obtained by putting (1,2,3,4,5) serially in the equation 8n+2

8*1+2=10, 8*2+2= 18, 8*3+2=26 , 8*4+2=34, 8*5+2= 42