Questions on Algebra: Square root, cubic root, N-th root answered by real tutors!

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Question 33217:
Found 2 solutions by sarah_adam, mszlmb:
Answer by sarah_adam(201) About Me  (Show Source):
You can put this solution on YOUR website!
3x%5E2-4x-5=0
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
a = 3 ;b = -4; c = -5
x+=+%28-%28-4%29+%2B-+sqrt%28+%28-4%29%5E2-4%2A%283%29%2A%28-5%29+%29%29%2F%282%2A3%29+
x+=+%284%29+%2B-+sqrt%28+16%2B60+%29%29%2F%282%2A3%29+
x+=+%284+%2B-+sqrt%28+76+%29%29%2F6
x+=+%284+%2B-+sqrt%284%2A19%29%29%2F6+
x+=+%284+%2B-+2sqrt%2819%29%29%2F6+
x+=+%282+%2B-+sqrt%2819%29%29%2F3+

Answer by mszlmb(115) About Me  (Show Source):
You can put this solution on YOUR website!
Hey check this out in case I do it wrong myself!

You know the quadratic formula is X+=+%28-B+%2B-+sqrt%28+B%5E2-4%2AA%2AC+%29%29%2F%282%2AA%29 .
You also know that A, B, and C come in the equation like this Ax^2+Bx+C.
In this case, A=3 B=-4 C=-5. You plug them in to the equation (replace letters with numbers) and we have X=++%28-%28-4%29+%2B-+sqrt%28+%28-4%29%5E2-4%2A%283%29%2A%28-5%29+%29%29%2F%282%2A%283%29%29 .
Well your answer breaks down to %284+%2B-+sqrt%28+16%2B60%29%29%2F6 .
[the four is positive because 2 negatives make a positive, the 16 is -4 squared, it's + 60 because -4*3*-5 = POSITIVE 60, and the 6 is 2*3.]
Now, we simplify the square root. sqrt%2876%29 is not an integer (whole number), so we simplify it.
76 is evenly divisible by 2, because its 1's place digit is evens. 76/2 is 38, so 38(2)=76. Still, 38 ends evenly, so it is also divisible by 2. 38/2=19. so 19(2)=38. Nineteen is a prime number, not evenly divisible by any whole numbers but 1 and itself. 19*2*2=76.
We have 2*2*19 as our primes. 2*2 is the same as 2%5E2 is the same as 4. sqrt%284%29 = 2, so we take 4's root (2) outside of the square root.
Our answer is %284+%2B-+2%2Asqrt%2819%29%29%2F6. One plus or minus can go, since either way we will plus or minus, and the 4,2, and 6 have a common factor of 2. The equation simplifies again to %282+%2B-+1%2Asqrt%2819%29%29%2F3. We don't need the one: %282+%2B-+sqrt%2819%29%29%2F3. The answers are %282%2Bsqrt%2819%29%29%2F3 and %282-sqrt%2819%29%29%2F3.
I'll allow your imagination to take over the second problem, the answers are 1/2 and 1. IM me if you need more help.