Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

EXPONENTIAL GRAPHS - PLEASE HELP!!

Can any one help me plz to solve y= ab^x if two points are ( 2,8) (0.5, 1)

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Original post by sykhan

Can any one help me plz to solve y= ab^x if two points are ( 2,8) (0.5, 1)

Well from those two points you are able to get two equations in

a

and

b

by simply substituting the coordinates into it. Try that.

so let y = 8 and x = 2

then repeat for the other coordinates.

Taking logs might make things easier...

I'd form the two equations, and divide one by the other - doesn't even need a calculator.

OP

When i divide both equation i got b^1.5= 8 now i dont know how to get rid of this decimal power. Plz help me

Original post by sykhan

When i divide both equation i got b^1.5= 8 now i dont know how to get rid of this decimal power. Plz help me

Square the whole thing.

OP

Original post by DFranklin

Taking logs might make things easier...

plz show me how?? Plz

OP

Can u solve the question for me plz as its gv me decimal power. And i dont know how to get rid of decimal power to get b.

Original post by sykhan

When i divide both equation i got b^1.5= 8 now i dont know how to get rid of this decimal power. Plz help me

at GCSE level, you can estimate roots; so you can take the square root of 8 as 2, and because root 2.5 is close to 2 and would give a greater answer, add on around 0.7/0.8 so you get 2.8.

At A-level it's completely different of couce

Form and solve the system of equations.

Original post by sykhan

When i divide both equation i got b^1.5= 8 now i dont know how to get rid of this decimal power. Plz help me

If you square the whole equation you get:

b^{1.5}\times b^{1.5}= 8\times 8

And using the rules for indices we have:

b^3=64

And you've eliminated the decimal part of the power.

Can you finish from there?

OP

Yes now i did it many thanks😊 so kind of u.

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