candice1 2 years ago jit4wonsolve each equation by completing the square. round to the nearest hundredth if necessary. 3. x^2+6x =16 4. x^2-10x =11 5. x^2-9x =0 6. x^2+16x =15 7. 3x^2+18x-81=0 use the quadratic formula to solve each equation. round to the nearest hundredth if necessary. 8. 4x^2+3x-8=0 9.2x^2-7x+3=0 10. x^2-2x+3=0 11. 2x^2+4x-7=0 I DONT GET THIS STUFF.

1. math456

so for quadratic stuff.. Use this formula..$-b \pm \sqrt{b ^{2}-4ac}/2a$ like for question 8: a=4; b=3; c=-8 <-- plug these number in the equation and solve..

2. candice1

i knew i was missing a formula lol. thanks.

3. math456

lol kk welcome.. for completing the sq..http://www.purplemath.com/modules/sqrquad.htm

4. math456

for ur question 3. $x ^{2}+6x=16$ $x ^{2}+6x+9$ is a complete sq. so u take 3 inside the brackets and take +9 to the other side.. like, $(x+3)^{2}=16+9$

5. math456

$(x+3)^{2}=25$ <-- take the sq. root on both sides.. $\sqrt{(x+3)^{2}}=\sqrt{5^{2}}$

6. math456

$x+3=\pm5$

7. candice1

are these the answers?

8. math456

x=5-3 ; x=-5-3 x=2 ; x=-8 No this is answer to question 3

9. candice1

oh okay thanks.

10. math456

y welcome

11. candice1

can you do the rest lol?

12. math456

try doing it, if you get stuck i will help u..

13. candice1

i tried and im stuck. and i have to turn these problems in in 20 mins and its a test.

14. beenthebest

X^2-6X=20 its saying round to the nearest hundredth can someone help me please