Question

plzz solve questions 5 and 6 from the quadratic equation . i will mark brainlist

Answer 1

5) Ans = 30
6) Ans Present age of son is 9 and father is 65

Solution 5:-

Let original price of book = x
let total book purchase (when price is x) = y

600/x = y .....(1)

According to question when price reduce to 5 then new price is (x-5) and no of books purchases (y+4)

(600/(x-5)) = (y+4) ...(2)

substitute value of eq (1) in (2) we get
(600/(x-5)) = (600/x)+4

open up brackets simplify equation and we get

$4 {x}^{2} - 20x - 3000 \: = 0$
simplfy it

${x}^{2} - 5x - 750 \: = 0$
${x}^{2} - 30x + 25x - 750 \: = 0$
x(x-30) +25(x-30) =0
(x-30)(x+25) =0
x=30

because x = -25 not possible


Solution 6:-

Let son age = x

According to question
Man age 1 year ago 8 times of son age

son age 1 year ago = x-1
Father age = 8(x-1)

Now father age is square of his son age

$8(x - 1) \: = \: {(x - 1)}^{2}$
open the brackets simplfy it and equation we get

${x}^{2} - 10x + 9 = 0$
${x}^{2} - 9x - x + 9 = 0$
x(x-9) -1(x-9) =0
(x-1) (x-9) =0

x=9
x=1 is not possible as it does not satisfy the condidtion

x=9 is current age if son
then current of father is 8(x-1)+1 = 8×(9-1)+1=65