Binomial Theorem HELPPP (1 Viewer)

[littlesmallworld]

in the expansion of (x+a)^3(x+b)^5, the coefficients of x^7 and c^6 are 9 and 12 respectively. Find the values of a and b

 

[Carrotsticks]

in the expansion of (x+a)^3(x+b)^5, the coefficients of x^7 and c^6 are 9 and 12 respectively. Find the values of a and b

Are you able to find the coefficients of x^7 and x^6?

If you can't, consider the many different ways you can acquire x^6 and x^7 ie:

x^0 * x^6 --> x^6

x^1 * x^5 --> x^6

etc

By letting the coeff of x^6 be 12 and letting the coeff of x^7 be 9, you will get two expressions in terms of A and B that you can solve simultaneously.

 

[littlesmallworld]

Are you able to find the coefficients of x^7 and x^6?

If you can't, consider the many different ways you can acquire x^6 and x^7 ie:

x^0 * x^6 --> x^6

x^1 * x^5 --> x^6

etc

By letting the coeff of x^6 be 12 and letting the coeff of x^7 be 9, you will get two expressions in terms of A and B that you can solve simultaneously.

Actually i got 3a + 5b = 9 and 10b^2 + 15ab + 3b^2 =12 for the coefficients

 

[Carrotsticks]

Actually i got 3a + 5b = 9 and 10b^2 + 15ab + 3b^2 =12 for the coefficients

Assuming that is correct, you should be able to solve that simultaneously via substitution.

 

[littlesmallworld]

Assuming that is correct, you should be able to solve that simultaneously via substitution.

Umm.. Could u pls walk me thru the steps?? I really suck at simultaneous

 

[panda15]

Umm.. Could u pls walk me thru the steps?? I really suck at simultaneous

Rearrange the first equation to make a the subject, then sove it into the second one and solve for b.

 

[RealiseNothing]

Umm.. Could u pls walk me thru the steps?? I really suck at simultaneous

You might want to fix that if you are doing MX1.