Question

This may end up being stupid but

Solving equations by Using the Zero Product Rule

I did it this way is this OK? Or...?
problem is : x(x+4)(10x-3)=0

x+4-4=0-4 10x-3+3=0+3 10/10x=3/10 x=3/10

then x^2+4x+10x^2-3x=0 set all x's to zero? Or is that entirely the wrong way to do this? Cos I am not sure what I should be doing. Thanks.

Answer 1

first you don't have subtract 4 yet
x(x+4)(10x-3)=0 its mean all is equal to 0
like this
x=0
(x+4)=0
10x -3 = 0
now solve for x

Answer 2

x(x+4)(10x-3)= 0
by the Zero Produce rule either one of the factors has to be zero - there are 3 factors x , x+4 and 10x - 3

so x = 0
or
x+4 = 0
or
10x - 3 = 0


so solving these 3 equations ;-
the solution set is x = 0 , -4 , 3/10

Answer 3

Now, what do I do if it has a number where that x is? LIke, 5(y-.4)(y+2.1)=0 ?

Answer 4

Is it the same thing?

Answer 5

no - its 5 times 9 y - 0.4) so y- 0.4 = 0 so y = 0.4

Answer 6

** thats not 9 thats (y - 0.4)