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Mathematics 7 Online
OpenStudy (anonymous):

help with square root problems???

OpenStudy (anonymous):

\[\sqrt{9y-196}+ \sqrt{196}=\sqrt{49}\]

OpenStudy (jdoe0001):

one may note that \(\bf 14^2 = 196\\ 7^2 = 49\)

OpenStudy (anonymous):

i know, so far i have \[\sqrt{9y-196} =-7\] i just dont know what to do from here

OpenStudy (jdoe0001):

raise both sides to the 2nd power

OpenStudy (jdoe0001):

\(\bf (\sqrt{9y-196})^2 =(-7)^2\)

OpenStudy (anonymous):

9y-196=49?

OpenStudy (jdoe0001):

yes

OpenStudy (anonymous):

so 245/9 is the answer?

OpenStudy (jdoe0001):

yes

OpenStudy (anonymous):

i just checked it and its not right

OpenStudy (jdoe0001):

hmm is this correct =>\(\bf \sqrt{9y-196}+ \sqrt{196}=\sqrt{49}\ \ \ ?\)

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

\[\sqrt{9y+196}+14=7 \implies \sqrt{9y+196}=-7\] square both sides

OpenStudy (anonymous):

i figured it out the answer is 49/3

OpenStudy (anonymous):

i mean \[\sqrt{9y-196}=-7\] \[(\sqrt{9y-196})^2=(-7)^2\]

OpenStudy (anonymous):

but maybe you could help with this one?\[\sqrt{x}(\sqrt{9}-\frac{ 4 }{ 3}=\sqrt{25}\]

OpenStudy (anonymous):

theres supposed to be a closed parenthesis after 4/3

OpenStudy (jdoe0001):

\(\bf \sqrt{x}\left(\sqrt{9}-\cfrac{ 4 }{ 3}\right)=\sqrt{25}\)

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

\[\sqrt{x}(\sqrt{9}-\frac{4}{3})=\sqrt{25}\] \[\text{since }\sqrt{9}=3,\sqrt{25}=5\] \[\sqrt{x}(3-\frac{4}{3})=5\] \[\sqrt{x}(\frac{5}{3})=5\] you can take it from here

OpenStudy (jdoe0001):

\(\bf \sqrt{x}\left(\sqrt{9}-\cfrac{ 4 }{ 3}\right)=\sqrt{25} \implies \sqrt{x} = \cfrac{\sqrt{25}}{\left(\sqrt{9}-\cfrac{ 4 }{ 3}\right)} \implies \sqrt{x} = \cfrac{\sqrt{25}}{\left(3-\cfrac{ 4 }{ 3}\right)}\)

OpenStudy (anonymous):

thank you so much!

OpenStudy (radar):

I still can't see the 49/3 as the solution to the first one!

OpenStudy (jdoe0001):

nor do I

OpenStudy (jdoe0001):

unless there's a typo

OpenStudy (anonymous):

\[\sqrt{x}=5\frac{3}{5}\] \[\sqrt x=3,x=9\]

OpenStudy (anonymous):

its a little complicated since \[\sqrt{9y-196}=-7\] you have to square both sides,\[-(7^2)=-49\] so, 9y-196=-49 9y=147 y=49/3

OpenStudy (anonymous):

lets take it from here \[\sqrt{9y-196}=-7\] \[9y-196=49\] \[9y=245,y=\frac{245}{9}\]

OpenStudy (anonymous):

i checked it and it works out 245/9 doesnt

OpenStudy (anonymous):

no when you square a negetive you always get positive \[(-a)^2=a^2\]

OpenStudy (anonymous):

so \[(-7)^2=7^2=49\]

OpenStudy (anonymous):

unless its-(7^2), i always learned that way too, but i mean if 49/3 works im just going to keep it. im guessing they wanted to keep the negative

OpenStudy (anonymous):

but if you go back to you equation and plug y-49/3 theres a negetive value in the square root!!!!!!!!!!!!!!!!!1problem

OpenStudy (anonymous):

if i get it worng then oh well, its just a homework question

OpenStudy (anonymous):

can you just recheck the way youtyped it in correctly

OpenStudy (anonymous):

i did it like 5 times haha im okay with it if i get one question wrong ha

OpenStudy (anonymous):

but would you want to help me with one more? you dont have to, if you dont want to

OpenStudy (anonymous):

\[\sqrt{135b^2c^3d}\times \sqrt{5b^2d}\] all the exponents are confusing me

OpenStudy (anonymous):

write evrything under the root seperatly ie \[\sqrt{abcd}=\sqrt{a}\sqrt{b}\sqrt{c}\sqrt{d}\]

OpenStudy (anonymous):

okay, before multiplying the two?

OpenStudy (anonymous):

\[\sqrt{135}\sqrt{b^2}\sqrt{c^3}\sqrt{d}\sqrt{5}\sqrt{b^2}\sqrt{d}\]

OpenStudy (anonymous):

yes now remember \[\sqrt{b^2}=b\] use this

OpenStudy (anonymous):

right do what do i do about the c^3

OpenStudy (anonymous):

right so**

OpenStudy (anonymous):

leave alone but multiply like terms it \[\sqrt{d}\times\sqrt{d}=d\] \[\sqrt{135}\times\sqrt{5}=\sqrt{135\times 5}=\sqrt{675}\]

OpenStudy (anonymous):

so i have \[\sqrt{675} \times b^2 \times \sqrt{c^3} \times d\]

OpenStudy (anonymous):

is that the answer?

OpenStudy (anonymous):

yes your a star

OpenStudy (anonymous):

thank you!!

OpenStudy (anonymous):

yw

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