Question

if a, b, c and d are in proportion, prove that: 7a +4b / 7c + 4d = 7a - 4b /7c - 4d

Answer 1

Answer:

7a+4b 7a- 4b

a+4b 7a- 4b--------- = -------------

a+4b 7a- 4b--------- = ------------- 7c+4d 7c- 4d

Step-by-step explanation:

a,b, c and d are in proportion

a c

----- = -----

b d

multiply numerator and denominator by 7 and 4 respectively both side

7a 7v

----- = -----

4b 4d

Applying compenedo and dividendo

we get

7a+4b 7c+4d

--------- = -------------

7a- 4b. 7c- 4d

hence the result

hence the result 7a+4b 7a- 4b

hence the result 7a+4b 7a- 4b--------- = -------------

hence the result 7a+4b 7a- 4b--------- = ------------- 7c+4d 7c- 4d