solving radical equations with one variable
in Algebra 1 Answers by

Your answer

Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:
To avoid this verification in future, please log in or register.

2 Answers

sqrt(3a+10)=sqrt(2a-1)+2

To remove the radical on the left-hand side of the equation, square both sides of the equation.
(~(3a+10))^(2)=(~(2a-1)+2)^(2)

Simplify the left-hand side of the equation.
3a+10=(~(2a-1)+2)^(2)

Squaring an expression is the same as multiplying the expression by itself 2 times.
3a+10=(~(2a-1)+2)(~(2a-1)+2)

Multiply each term in the first group by each term in the second group using the FOIL method. FOIL stands for First Outer Inner Last, and is a method of multiplying two binomials.  First, multiply the first two terms in each binomial group.  Next, multiply the outer terms in each group, followed by the inner terms.  Finally, multiply the last two terms in each group.
3a+10=(~(2a-1)*~(2a-1)+~(2a-1)*2+2*~(2a-1)+2*2)

Simplify the FOIL expression by multiplying and combining all like terms.
3a+10=(~(2a-1)^(2)+4~(2a-1)+4)

Remove the parentheses around the expression ~(2a-1)^(2)+4~(2a-1)+4.
3a+10=~(2a-1)^(2)+4~(2a-1)+4

Raising a square root to the square power results in the expression inside the root.
3a+10=(2a-1)+4~(2a-1)+4

Add 4 to -1 to get 3.
3a+10=2a+3+4~(2a-1)

Since a is on the right-hand side of the equation, switch the sides so it is on the left-hand side of the equation.
2a+3+4~(2a-1)=3a+10

Move all terms not containing ~(2a-1) to the right-hand side of the equation.
4~(2a-1)=-2a-3+3a+10

Simplify the right-hand side of the equation.
4~(2a-1)=a+7

Divide each term in the equation by 4.
(4~(2a-1))/(4)=(a)/(4)+(7)/(4)

Simplify the left-hand side of the equation by canceling the common terms.
~(2a-1)=(a)/(4)+(7)/(4)

To remove the radical on the left-hand side of the equation, square both sides of the equation.
(~(2a-1))^(2)=((a)/(4)+(7)/(4))^(2)

Simplify the left-hand side of the equation.
2a-1=((a)/(4)+(7)/(4))^(2)

Combine the numerators of all expressions that have common denominators.
2a-1=((a+7)/(4))^(2)

Expand the exponent of 2 to the inside factor (a+7).
2a-1=((a+7)^(2))/((4)^(2))

Expand the exponent 2 to 4.
2a-1=((a+7)^(2))/(4^(2))

Simplify the exponents of 4^(2).
2a-1=((a+7)^(2))/(16)

Multiply each term in the equation by 16.
2a*16-1*16=((a+7)^(2))/(16)*16

Simplify the left-hand side of the equation by multiplying out all the terms.
32a-16=((a+7)^(2))/(16)*16

Simplify the right-hand side of the equation by simplifying each term.
32a-16=(a+7)^(2)

Since (a+7)^(2) contains the variable to solve for, move it to the left-hand side of the equation by subtracting (a+7)^(2) from both sides.
32a-16-(a+7)^(2)=0

Squaring an expression is the same as multiplying the expression by itself 2 times.
32a-16-((a+7)(a+7))=0

Multiply -1 by each term inside the parentheses.
32a-16-a^(2)-14a-49=0

Since 32a and -14a are like terms, add -14a to 32a to get 18a.
18a-16-a^(2)-49=0

Subtract 49 from -16 to get -65.
18a-65-a^(2)=0

Move all terms not containing a to the right-hand side of the equation.
-a^(2)+18a-65=0

Multiply each term in the equation by -1.
a^(2)-18a+65=0

For a polynomial of the form x^(2)+bx+c, find two factors of c (65) that add up to b (-18).  In this problem -5*-13=65 and -5-13=-18, so insert -5 as the right hand term of one factor and -13 as the right-hand term of the other factor.
(a-5)(a-13)=0

Set each of the factors of the left-hand side of the equation equal to 0.
a-5=0_a-13=0

Since -5 does not contain the variable to solve for, move it to the right-hand side of the equation by adding 5 to both sides.
a=5_a-13=0

Set each of the factors of the left-hand side of the equation equal to 0.
a=5_a-13=0

Since -13 does not contain the variable to solve for, move it to the right-hand side of the equation by adding 13 to both sides.
a=5_a=13

The complete solution is the set of the individual solutions.
a=5,13
by Level 6 User (23.6k points)

The first thing to realise is that, since we can only have a real square root of a positive number, then 3a+10 and 2a-1 must be positive so a must be greater than -10/3 and greater than 1/2. That just means of course that a is bigger than 1/2, since 1/2 is already bigger than -10/3.  Now, square both sides of the equation.

3a+10=2a-1+4+4sqrt(2a-1)

a+7=4sqrt(2a-1)

Square both sides again.

a^2+14a+49=32a-16 which becomes the quadratic equation a^2-18a+65=0. This factorises into (a-5)(a-13)=0, from which a=5 and 13, both of which satisfy the requirements for keeping the square root expressions positive. Substituting these values for a in the original question we can see that they both fit.

by Top Rated User (1.1m points)

Related questions

1 answer
asked May 5, 2019 in Trigonometry Answers by anonymous | 399 views
1 answer
asked Sep 26, 2019 in Algebra 1 Answers by solid | 779 views
1 answer
asked Apr 23, 2019 by anonymous | 1.1k views
1 answer
asked Feb 21, 2019 in Trigonometry Answers by Gay boi | 4.0k views
1 answer
asked Oct 1, 2014 in Algebra 1 Answers by anonymous | 642 views
1 answer
1 answer
asked Jun 6, 2014 in Pre-Algebra Answers by anonymous | 470 views
1 answer
asked Nov 18, 2013 in Algebra 2 Answers by Aarush Level 1 User (160 points) | 560 views
1 answer
asked Nov 8, 2013 in order of operations by anonymous | 501 views
1 answer
asked Oct 7, 2013 in Pre-Algebra Answers by anonymous | 475 views
3 answers
1 answer
asked Jun 26, 2013 in Algebra 2 Answers by anonymous | 678 views
1 answer
asked Jun 21, 2013 in Algebra 2 Answers by anonymous | 1.8k views
1 answer
asked Jun 20, 2013 in Algebra 1 Answers by anonymous | 635 views
1 answer
asked May 23, 2013 in Algebra 1 Answers by anonymous | 551 views
Welcome to MathHomeworkAnswers.org, where students, teachers and math enthusiasts can ask and answer any math question. Get help and answers to any math problem including algebra, trigonometry, geometry, calculus, trigonometry, fractions, solving expression, simplifying expressions and more. Get answers to math questions. Help is always 100% free!
87,544 questions
99,732 answers
2,417 comments
482,895 users