Question
Find the roots
y1=21−17,y2=21+17
Alternative Form
y1≈−1.561553,y2≈2.561553
Evaluate
y2−y−4
To find the roots of the expression,set the expression equal to 0
y2−y−4=0
Substitute a=1,b=−1 and c=−4 into the quadratic formula y=2a−b±b2−4ac
y=21±(−1)2−4(−4)
Simplify the expression
More Steps

Evaluate
(−1)2−4(−4)
Evaluate the power
1−4(−4)
Multiply the numbers
More Steps

Evaluate
4(−4)
Multiplying or dividing an odd number of negative terms equals a negative
−4×4
Multiply the numbers
−16
1−(−16)
If a negative sign or a subtraction symbol appears outside parentheses, remove the parentheses and change the sign of every term within the parentheses
1+16
Add the numbers
17
y=21±17
Separate the equation into 2 possible cases
y=21+17y=21−17
Solution
y1=21−17,y2=21+17
Alternative Form
y1≈−1.561553,y2≈2.561553
Show Solution
