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Size:  32.4 KBI got to part (b) and now I'm stuck. I have a+b = 7 and -8a+4b = 4 and now I don't know how to go about getting the value of a and b
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    ah this is simultaneous equations from c1. firstly you must make one term from each equation the same (id recommend multiplying all of a+b=7 by 4, but you can do this slightly differently by x -8 and eliminating a).
    this leaves you with -8a+4b=4 and 4a+4b=28
    because the both 4b's are positive, you subtract the second equation from the first.
    -8a - 4a= -12a
    4b-4b=0 (eliminating the term)
    4-28=-24
    now we have -12a=-24, solving gives a=2.
    now substitute a=2 into ur a+b=7 to get 2+b=7
    b=5 (therefore a=2,b=5)
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    (Original post by Toasticide)
    ah this is simultaneous equations from c1. firstly you must make one term from each equation the same (id recommend multiplying all of a+b=7 by 4, but you can do this slightly differently by x -8 and eliminating a).
    this leaves you with -8a+4b=4 and 4a+4b=28
    because the both 4b's are positive, you subtract the second equation from the first.
    -8a - 4a= -12a
    4b-4b=0 (eliminating the term)
    4-28=-24
    now we have -12a=-24, solving gives a=2.
    now substitute a=2 into ur a+b=7 to get 2+b=7
    b=5 (therefore a=2,b=5)
    Thankyou so much!! I don't know why I didn't think of simultaneous equations, dumb moment obviously
 
 
 
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