How do you solve x( 5x - 2) = 24x(5x2)=24?

1 Answer
May 1, 2018

x=12/5 or 2.4 , -2x=125or2.4,2

Explanation:

expand:

x(5x-2) -> 5x^2-2x=24x(5x2)5x22x=24

set equal to 00:

5x^2-2x=24 -> 5x^2-2x-24=05x22x=245x22x24=0

factorise:

-> 5x^2+10x-12x-245x2+10x12x24

-> 5x(x+2)-12(x+2)5x(x+2)12(x+2)

rArr (x+2)(5x-12)(x+2)(5x12)

Check to see if correct:

(5x-12)(x+2)=5x^2+10x-12x-24(5x12)(x+2)=5x2+10x12x24

-> 5x^2-2x-245x22x24.

set each bracket equal to 00:

5x-12=05x12=0

-> 5x=125x=12

rArr x=12/5x=125

x+2=0x+2=0

rArr x=-2x=2

Check these values:

2.4(5 xx 2.4-2)=2.4 xx 10=242.4(5×2.42)=2.4×10=24

-2(5 xx-2-2)2(5×22)=-2 xx -12=24#

therefore these values are correct.