# Step-by-step Solution

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

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### Videos

$x^2-3x-4$

## Step-by-step solution

Problem to solve:

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

Solving method

1

The product of two binomials of the form $(x+a)(x+b)$ is equal to the product of the first terms of the binomials, plus the algebraic sum of the second terms by the common term of the binomials, plus the product of the second terms of the binomials. In other words: $(x+a)(x+b)=x^2+(a+b)x+ab$

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

Subtract the values $1$ and $-4$

$x^2-3x+1\cdot -4$
3

Multiply $1$ times $-4$

$x^2-3x-4$

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

Special products

~ 0.05 s