How do you solve \sqrt { 5v - 9} = v - 15v9=v1?

2 Answers
Sep 28, 2017

Eliminate the radical by squaring both sides of the equation
Combine like terms
Solve the resulting quadratic
Check the answers.

Explanation:

Eliminate the radical by squaring both sides of the equation

5v -9 = v^2 - 2v + 15v9=v22v+1

Combine like terms:

v^2-7v+10 = 0v27v+10=0

Solve the resulting quadratic:

(v - 2)(v - 5) = 0(v2)(v5)=0

v = 2 and v = 5v=2andv=5

Check both answers:

sqrt(5(2)-9) = 2-15(2)9=21

sqrt(1) = 11=1

1 = 11=1

sqrt(5(5)-9) = 5-15(5)9=51

sqrt(16) = 416=4

4 = 44=4

Both answers check.

Sep 28, 2017

v=2v=2 or v=5v=5

Explanation:

sqrt(5v-9)=v-15v9=v1 This type of equation is called 'Radical equation'.

Step 1) Square both sides of the equation to eliminate square root.
[sqrt(5v-9)]^2=(v-1)^2[5v9]2=(v1)2

Step 2) Use FOIL and simplify
|5v-9|=v^2-2v+1|5v9|=v22v+1

Step 3) Consider when |5v-9||5v9| is positive or negative, then simplify.

i) 5v-9>05v9>0, v>9/5v>95

5v-9=v^2-2v+15v9=v22v+1
−v^2+7v−10=0v2+7v10=0
v^2-7v+10=0v27v+10=0

Factor left side of the equation
(v-5)(v-2)=0(v5)(v2)=0
v-5=0v5=0 or v-2=0v2=0

∴v=2 or v=5
Check if it satisfies range v>9/5 (Yes)
∴v=2 or v=5(∵v>9/5) ------------- 1

ii) 5v-9<0, v<9/5
-(5v-9)=v^2-2v+1
v^2+3v+8=0

Use quadratic formula
v=-(3±sqrt41)/2
Check if it satisfies range v<9/5 (Yes)
But if you substitute v=-(3±sqrt41)/2 to sqrt(5v-9)=v-1, It won't satisfy the equation.

No Solution (∵Doesn't satisfies when you substitute the value.) ------------- 2

Moderate 1 and 2,

∴v=2 or v=5