Evaluate the expression below when x = -4.
4x2 - 2x × 15

Question

Evaluate the expression below when x = -4.
 4x2 - 2x × 15

anonymous · Answer

is that -2x multiplied by 15?
Sorry it just looks like an extra variable like that

anonymous · Answer

Oh I know this.

anonymous · Answer

64+90=154

anonymous · Answer

explain how ya got that, it's kind of required and a lot more useful than giving the answer

anonymous · Answer

4x^2 - 2x × 15
4x^2 - 2x(15)

put a (  ) around each x
4(x)^2 - 2(x)(15)

replace each x with -4
4(-4)^2 - 2(-4)(15)

anonymous · Answer

yeah it's multiplied bby 15 jade

anonymous · Answer

Yeah, basically what @DemolisionWolf just showed you
then you just simplify, but remember PEMDAS so do the multiplication before you do the 4(-4)^2 - 2(-4)

anonymous · Answer

-56 ?

anonymous · Answer

well, what's 8 multiplied by 15? (-2 * -4 = 8)

anonymous · Answer

8 multiplied by 15 is 120

anonymous · Answer

okay so 4(-4) squared minus 120 is the answer
so what's 4 multiplied by -4?

anonymous · Answer

4(-4)^2 - 2(-4)(15)

4(16) - 2(-4)(15)

64 - 2(-4)(15)

64 - (-8)(15)

64 - (-120)

64 + 120

anonymous · Answer

184 ?

anonymous · Answer

yep :P

anonymous · Answer

thanks

anonymous · Answer

only took 15 minutes for one question

anonymous · Answer

thats how math goes when you learn it. its the same for everyone when the start, you are in good company ^_^