Question
Solve the inequality
Solve the inequality by testing the values in the interval
Solve the inequality by separating into cases
Solve for z
91≤z≤1
Alternative Form
z∈[91,1]
Evaluate
9z2≤10z−1
Move the expression to the left side
9z2−(10z−1)≤0
If a negative sign or a subtraction symbol appears outside parentheses, remove the parentheses and change the sign of every term within the parentheses
9z2−10z+1≤0
Rewrite the expression
9z2−10z+1=0
Factor the expression
More Steps

Evaluate
9z2−10z+1
Rewrite the expression
9z2+(−1−9)z+1
Calculate
9z2−z−9z+1
Rewrite the expression
z×9z−z−9z+1
Factor out z from the expression
z(9z−1)−9z+1
Factor out −1 from the expression
z(9z−1)−(9z−1)
Factor out 9z−1 from the expression
(z−1)(9z−1)
(z−1)(9z−1)=0
When the product of factors equals 0,at least one factor is 0
z−1=09z−1=0
Solve the equation for z
More Steps

Evaluate
z−1=0
Move the constant to the right-hand side and change its sign
z=0+1
Removing 0 doesn't change the value,so remove it from the expression
z=1
z=19z−1=0
Solve the equation for z
More Steps

Evaluate
9z−1=0
Move the constant to the right-hand side and change its sign
9z=0+1
Removing 0 doesn't change the value,so remove it from the expression
9z=1
Divide both sides
99z=91
Divide the numbers
z=91
z=1z=91
Determine the test intervals using the critical values
z<9191<z<1z>1
Choose a value form each interval
z1=−1z2=95z3=2
To determine if z<91 is the solution to the inequality,test if the chosen value z=−1 satisfies the initial inequality
More Steps

Evaluate
9(−1)2≤10(−1)−1
Simplify
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Evaluate
9(−1)2
Evaluate the power
9×1
Any expression multiplied by 1 remains the same
9
9≤10(−1)−1
Simplify
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Evaluate
10(−1)−1
Simplify
−10−1
Subtract the numbers
−11
9≤−11
Check the inequality
false
z<91 is not a solutionz2=95z3=2
To determine if 91<z<1 is the solution to the inequality,test if the chosen value z=95 satisfies the initial inequality
More Steps

Evaluate
9(95)2≤10×95−1
Multiply the terms
More Steps

Evaluate
9(95)2
Evaluate the power
9×8125
Multiply the numbers
925
925≤10×95−1
Simplify
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Evaluate
10×95−1
Multiply the numbers
950−1
Reduce fractions to a common denominator
950−99
Write all numerators above the common denominator
950−9
Subtract the numbers
941
925≤941
Calculate
2.7˙≤941
Calculate
2.7˙≤4.5˙
Check the inequality
true
z<91 is not a solution91<z<1 is the solutionz3=2
To determine if z>1 is the solution to the inequality,test if the chosen value z=2 satisfies the initial inequality
More Steps

Evaluate
9×22≤10×2−1
Multiply the terms
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Evaluate
9×22
Evaluate the power
9×4
Multiply the numbers
36
36≤10×2−1
Simplify
More Steps

Evaluate
10×2−1
Multiply the numbers
20−1
Subtract the numbers
19
36≤19
Check the inequality
false
z<91 is not a solution91<z<1 is the solutionz>1 is not a solution
The original inequality is a nonstrict inequality,so include the critical value in the solution
91≤z≤1 is the solution
Solution
91≤z≤1
Alternative Form
z∈[91,1]
Show Solution
