Question

The square of a negative number is twenty-eight more than three times the negative number. Find the number.

Answer 1

-4 that's the end result

Answer 2

the number is x

it is negative
the square is 28 more than 3 times itself
x²=28+3x
minus (28+3x)
x²-3x-28=0
factor
(x-7)(x+4)=0
set to zero

x-7=0
x=7
this is not the answer because we were told the number was negative


x+4=0
x=-4
correct

the number is -4
test
(-4)²=28+3(-4)
16=28-12
16=16
check


the number is -4