Algebra
Calculus
Trigonometry
Matrix
Question
Factor the expression
(z−5)(z+4)
Evaluate
z2−z−20
Rewrite the expression
z2+(4−5)z−20
Calculate
z2+4z−5z−20
Rewrite the expression
z×z+z×4−5z−5×4
Factor out z from the expression
z(z+4)−5z−5×4
Factor out −5 from the expression
z(z+4)−5(z+4)
Solution
(z−5)(z+4)
Show Solution
Find the roots
z1=−4,z2=5
Evaluate
z2−z−20
To find the roots of the expression,set the expression equal to 0
z2−z−20=0
Factor the expression
More Steps
Evaluate
z2−z−20
Rewrite the expression
z2+(4−5)z−20
Calculate
z2+4z−5z−20
Rewrite the expression
z×z+z×4−5z−5×4
Factor out z from the expression
z(z+4)−5z−5×4
Factor out −5 from the expression
z(z+4)−5(z+4)
Factor out z+4 from the expression
(z−5)(z+4)
(z−5)(z+4)=0
When the product of factors equals 0,at least one factor is 0
z−5=0z+4=0
Solve the equation for z
More Steps
Evaluate
z−5=0
Move the constant to the right-hand side and change its sign
z=0+5
Removing 0 doesn't change the value,so remove it from the expression
z=5
z=5z+4=0
Solve the equation for z
More Steps
Evaluate
z+4=0
Move the constant to the right-hand side and change its sign
z=0−4
Removing 0 doesn't change the value,so remove it from the expression
z=−4
z=5z=−4
Solution
z1=−4,z2=5
Show Solution