Algebra
Calculus
Trigonometry
Matrix
Question
Factor the expression
(k−5)(k+4)
Evaluate
k2−k−20
Rewrite the expression
k2+(4−5)k−20
Calculate
k2+4k−5k−20
Rewrite the expression
k×k+k×4−5k−5×4
Factor out k from the expression
k(k+4)−5k−5×4
Factor out −5 from the expression
k(k+4)−5(k+4)
Solution
(k−5)(k+4)
Show Solution
Find the roots
k1=−4,k2=5
Evaluate
k2−k−20
To find the roots of the expression,set the expression equal to 0
k2−k−20=0
Factor the expression
More Steps
Evaluate
k2−k−20
Rewrite the expression
k2+(4−5)k−20
Calculate
k2+4k−5k−20
Rewrite the expression
k×k+k×4−5k−5×4
Factor out k from the expression
k(k+4)−5k−5×4
Factor out −5 from the expression
k(k+4)−5(k+4)
Factor out k+4 from the expression
(k−5)(k+4)
(k−5)(k+4)=0
When the product of factors equals 0,at least one factor is 0
k−5=0k+4=0
Solve the equation for k
More Steps
Evaluate
k−5=0
Move the constant to the right-hand side and change its sign
k=0+5
Removing 0 doesn't change the value,so remove it from the expression
k=5
k=5k+4=0
Solve the equation for k
More Steps
Evaluate
k+4=0
Move the constant to the right-hand side and change its sign
k=0−4
Removing 0 doesn't change the value,so remove it from the expression
k=−4
k=5k=−4
Solution
k1=−4,k2=5
Show Solution