# Step-by-step Solution

## Solve the product $\left(x+1\right)\left(x-4\right)$

Go!
1
2
3
4
5
6
7
8
9
0
a
b
c
d
f
g
m
n
u
v
w
x
y
z
.
(◻)
+
-
×
◻/◻
/
÷
2

e
π
ln
log
log
lim
d/dx
Dx
|◻|
=
>
<
>=
<=
sin
cos
tan
cot
sec
csc

asin
acos
atan
acot
asec
acsc

sinh
cosh
tanh
coth
sech
csch

asinh
acosh
atanh
acoth
asech
acsch

### Videos

$x^2-3x-4$

## Step-by-step explanation

Problem to solve:

$\left(x+1\right)\left(x-4\right)$

Choose the solving method

1

We can multiply the polynomials $\left(x+1\right)\left(x-4\right)$ by using the FOIL method. The acronym F O I L stands for multiplying the terms in each bracket in the following order: First by First ($F\times F$), Outer by Outer ($O\times O$), Inner by Inner ($I\times I$), Last by Last ($L\times L$):

• ($F\times F$) is $(x)(x)$
• ($O\times O$) is $(x)(-4)$
• ($I\times I$) is $(1)(x)$
• ($L\times L$) is $(1)(-4)$

Then, combine the four terms in a sum: $(F\times F) + (O\times O) + (I\times I) + (L\times L)$:

$x\cdot x-4x+1x+1\cdot -4$
2

Multiply $1$ times $-4$

$x\cdot x-4x+1x-4$
3

Any expression multiplied by $1$ is equal to itself

$x\cdot x-4x+x-4$
4

When multiplying two powers that have the same base ($x$), you can add the exponents

$x^2-4x+x-4$
5

Combining like terms $-4x$ and $x$

$x^2-3x-4$

$x^2-3x-4$
$\left(x+1\right)\left(x-4\right)$