Math Is Fun Forum

soha

Real Member

Registered: 2006-07-07

Posts: 2,530

Answer

pls solve :-

A) (x+4)² -(x+5)² =9
B)0.5x+ x/3=0.25x+7
C)x+0.7x/2=0.85

the answers r given in my text, but i want the method to solve the above problems

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"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!"
- David O. McKay

Khushboo

Member

Registered: 2007-10-16

Posts: 47

Re: Answer

The above equation can be written as
=> (x+4-x-5)(x+4+x+5)=9
=>(-1)(2x+9)=9
=>-2x-9=9
=>-2x=18
or x=-9
now plug in the values in the both sides of the equation to check whether your answer is correct or not
LHS =>(-9+4)^2-(-9+5)^2
       =>25-16
       OR 9
RHS =>9

The value is correct.

b)0.5x can be written as 1/2x, similarly 0.25x can be written as 1/4x
=>1/2x+x/3-1/4x=7
=>6x+4x-3x/12=7
=>7x/12=7
or x=12

plug 12 in place of x to check the equality of the equation.

c) 27x/20=85/100
=>27x=85/100*20
=>27x=85/5
=>27x=17
or x=17/27

hope you will find the process simple enough

khushboo

soha

Real Member

Registered: 2006-07-07

Posts: 2,530

Re: Answer

A) in my text answer is 1
please check whether this is correct:-

(x+4)² -(x-5)² =9
x²+8x+16-(x²-10x+25)=9
8x+16+10x-25=9
18x-9=9
18x-18=0
x-1=0
x=1

is this correct????????

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"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!"
- David O. McKay

Khushboo

Member

Registered: 2007-10-16

Posts: 47

Re: Answer

The equation you wrote in the beginning was (x+4)^2-(x+5)^2=9

what you are writing write now is (x+4)² -(x-5)² =9, so please check the question. If the ist equation holds good then the answer should be x=-9 and if the second equation holds good then x=1 will be correct.

please check the question