# Math Help - Quadratic Equations - help needed

1. ## Quadratic Equations - help needed

Need help on this question:

Solve 4y4 - 7y2 - 36 = 0
y =

Also need help with this question:
Solve (square root of 3s +4) + 2s = 12
s =

Also need help with this question:
Solve (square root of 17 - 2x) = (square root of 8 - x) + 1
x =

Also need help with this problem:
Solve: Let u = (square root of x-2)

(square root of x-2) squared - 12 (square root of x) + 51 = 0
x =

Hope someone can help.

2. ## Re: Quadratic Equations - help needed

For the first problem, substitute w=y^2 and then you have a quadratic equation in w, which you can easily solve. Once you find the two values for w, then y = +/- sqrt(w).

For the next few rearrange so that you can square and get rid of the square root signs. For example starting with:
sqrt{3s+4}+2s=12, bring the 2s term to the right and square both sides to get 3s+4=(12-2s)^2
= 144-48s+4s^2. Now you can solve as usual.

For the last two square both sides, and you'll end up with a square root term. Rearrange to get that term by itself, and as above square again and rearrange. Also consider doing the w=x^2 substitution to get a quadratic. Hope this helps.